623421 has 12 divisors (see below), whose sum is σ = 909948. Its totient is φ = 411264.

The previous prime is 623417. The next prime is 623423. The reversal of 623421 is 124326.

It is a happy number.

623421 is a `hidden beast` number, since 623 + 42 + 1 = 666.

623421 is digitally balanced in base 2 and base 7, because in such bases it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 5625 + 617796 = 75^2 + 786^2 .

It is not a de Polignac number, because 623421 - 2² = 623417 is a prime.

It is a hoax number, since the sum of its digits (18) coincides with the sum of the digits of its distinct prime factors.

It is an Ulam number.

623421 is strictly pandigital in base 7.

623421 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 623394 and 623403.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 623421.

It is not an unprimeable number, because it can be changed into a prime (623423) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 711 + ... + 1323.

It is an arithmetic number, because the mean of its divisors is an integer number (75829).

2⁶²³⁴²¹ is an apocalyptic number.

It is an amenable number.

623421 is a deficient number, since it is larger than the sum of its proper divisors (286527).

623421 is a wasteful number, since it uses less digits than its factorization.

623421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 732 (or 729 counting only the distinct ones).

The product of its digits is 288, while the sum is 18.

The square root of 623421 is about 789.5701362134. The cubic root of 623421 is about 85.4267352266.

Adding to 623421 its reverse (124326), we get a palindrome (747747).

The spelling of 623421 in words is "six hundred twenty-three thousand, four hundred twenty-one".