621321021 has 6 divisors (see below), whose sum is σ = 897463710. Its totient is φ = 414214008.

The previous prime is 621321013. The next prime is 621321047. The reversal of 621321021 is 120123126.

621321021 is a `hidden beast` number, since 621 + 3 + 21 + 0 + 21 = 666.

It can be written as a sum of positive squares in only one way, i.e., 436224996 + 185096025 = 20886^2 + 13605^2 .

It is not a de Polignac number, because 621321021 - 2³ = 621321013 is a prime.

It is a super-2 number, since 2×621321021² = 772079622272964882, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 621320985 and 621321003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (621321721) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 34517826 + ... + 34517843.

It is an arithmetic number, because the mean of its divisors is an integer number (149577285).

Almost surely, 2^621321021 is an apocalyptic number.

It is an amenable number.

621321021 is a deficient number, since it is larger than the sum of its proper divisors (276142689).

621321021 is a wasteful number, since it uses less digits than its factorization.

621321021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 69035675 (or 69035672 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

The square root of 621321021 is about 24926.3118210456. The cubic root of 621321021 is about 853.3070800673.

Adding to 621321021 its reverse (120123126), we get a palindrome (741444147).

The spelling of 621321021 in words is "six hundred twenty-one million, three hundred twenty-one thousand, twenty-one".