21123645655504 has 60 divisors (see below), whose sum is σ = 47609614137888. Its totient is φ = 9052880491200.

The previous prime is 21123645655477. The next prime is 21123645655603. The reversal of 21123645655504 is 40555654632112.

It is a hoax number, since the sum of its digits (49) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (49).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 121096509 + ... + 121270819.

Almost surely, 2^{21123645655504} is an apocalyptic number.

It is an amenable number.

21123645655504 is an abundant number, since it is smaller than the sum of its proper divisors (26485968482384).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21123645655504 is a wasteful number, since it uses less digits than its factorization.

21123645655504 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 328904 (or 328891 counting only the distinct ones).

The product of its (nonzero) digits is 4320000, while the sum is 49.

The spelling of 21123645655504 in words is "twenty-one trillion, one hundred twenty-three billion, six hundred forty-five million, six hundred fifty-five thousand, five hundred four".