645621104421 has 24 divisors (see below), whose sum is σ = 952540917120. Its totient is φ = 421196472576.

The previous prime is 645621104419. The next prime is 645621104473. The reversal of 645621104421 is 124401126546.

645621104421 is a `hidden beast` number, since 6 + 4 + 5 + 621 + 1 + 0 + 4 + 4 + 21 = 666.

It is not a de Polignac number, because 645621104421 - 2¹ = 645621104419 is a prime.

It is a super-2 number, since 2×645621104421² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645621104411) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2975925 + ... + 3185493.

It is an arithmetic number, because the mean of its divisors is an integer number (39689204880).

Almost surely, 2^645621104421 is an apocalyptic number.

It is an amenable number.

645621104421 is a deficient number, since it is larger than the sum of its proper divisors (306919812699).

645621104421 is a wasteful number, since it uses less digits than its factorization.

645621104421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 216905 (or 216902 counting only the distinct ones).

The product of its (nonzero) digits is 46080, while the sum is 36.

The spelling of 645621104421 in words is "six hundred forty-five billion, six hundred twenty-one million, one hundred four thousand, four hundred twenty-one".