642621 has 16 divisors (see below), whose sum is σ = 995328. Its totient is φ = 361200.

The previous prime is 642613. The next prime is 642623. The reversal of 642621 is 126246.

It is a happy number.

It is not a de Polignac number, because 642621 - 2³ = 642613 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642623) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1276 + ... + 1706.

It is an arithmetic number, because the mean of its divisors is an integer number (62208).

2⁶⁴²⁶²¹ is an apocalyptic number.

It is an amenable number.

642621 is a deficient number, since it is larger than the sum of its proper divisors (352707).

642621 is a wasteful number, since it uses less digits than its factorization.

642621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 512.

The product of its digits is 576, while the sum is 21.

The square root of 642621 is about 801.6364512670. The cubic root of 642621 is about 86.2948684842.

Adding to 642621 its reverse (126246), we get a palindrome (768867).

The spelling of 642621 in words is "six hundred forty-two thousand, six hundred twenty-one".