21645004664 has 16 divisors (see below), whose sum is σ = 40586497200. Its totient is φ = 10821938752.

The previous prime is 21645004651. The next prime is 21645004669. The reversal of 21645004664 is 46640054612.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21645004669) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 124517 + ... + 242475.

It is an arithmetic number, because the mean of its divisors is an integer number (2536656075).

Almost surely, 2^21645004664 is an apocalyptic number.

It is an amenable number.

21645004664 is a deficient number, since it is larger than the sum of its proper divisors (18941492536).

21645004664 is a wasteful number, since it uses less digits than its factorization.

21645004664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 140902 (or 140898 counting only the distinct ones).

The product of its (nonzero) digits is 138240, while the sum is 38.

The spelling of 21645004664 in words is "twenty-one billion, six hundred forty-five million, four thousand, six hundred sixty-four".