21551901795 has 64 divisors (see below), whose sum is σ = 38769269760. Its totient is φ = 11358406656.

The previous prime is 21551901779. The next prime is 21551901803. The reversal of 21551901795 is 59710915512.

It is a happy number.

21551901795 is a `hidden beast` number, since 2 + 1 + 551 + 9 + 0 + 1 + 7 + 95 = 666.

It is not a de Polignac number, because 21551901795 - 2⁴ = 21551901779 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 21551901795.

It is an unprimeable number.

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 63 ways as a sum of consecutive naturals, for example, 7827139 + ... + 7829891.

It is an arithmetic number, because the mean of its divisors is an integer number (605769840).

Almost surely, 2^21551901795 is an apocalyptic number.

21551901795 is a deficient number, since it is larger than the sum of its proper divisors (17217367965).

21551901795 is a wasteful number, since it uses less digits than its factorization.

21551901795 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3433 (or 3427 counting only the distinct ones).

The product of its (nonzero) digits is 141750, while the sum is 45.

The spelling of 21551901795 in words is "twenty-one billion, five hundred fifty-one million, nine hundred one thousand, seven hundred ninety-five".