621563921 has 8 divisors (see below), whose sum is σ = 678888000. Its totient is φ = 564376240.

The previous prime is 621563893. The next prime is 621563923. The reversal of 621563921 is 129365126.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 621563921 - 2¹⁸ = 621301777 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (621563923) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 24446 + ... + 42903.

It is an arithmetic number, because the mean of its divisors is an integer number (84861000).

Almost surely, 2^621563921 is an apocalyptic number.

It is an amenable number.

621563921 is a deficient number, since it is larger than the sum of its proper divisors (57324079).

621563921 is a wasteful number, since it uses less digits than its factorization.

621563921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 68199.

The product of its digits is 19440, while the sum is 35.

The square root of 621563921 is about 24931.1837063546. The cubic root of 621563921 is about 853.4182632178.

The spelling of 621563921 in words is "six hundred twenty-one million, five hundred sixty-three thousand, nine hundred twenty-one".