21025115055 has 64 divisors (see below), whose sum is σ = 42769413120. Its totient is φ = 9599845248.

The previous prime is 21025115053. The next prime is 21025115099. The reversal of 21025115055 is 55051152012.

21025115055 is a `hidden beast` number, since 2 + 102 + 51 + 1 + 505 + 5 = 666.

It is not a de Polignac number, because 21025115055 - 2¹ = 21025115053 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21025115053) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 793044 + ... + 819126.

It is an arithmetic number, because the mean of its divisors is an integer number (668272080).

Almost surely, 2^21025115055 is an apocalyptic number.

21025115055 is an abundant number, since it is smaller than the sum of its proper divisors (21744298065).

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

21025115055 is a wasteful number, since it uses less digits than its factorization.

21025115055 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26957 (or 26951 counting only the distinct ones).

The product of its (nonzero) digits is 2500, while the sum is 27.

Adding to 21025115055 its reverse (55051152012), we get a palindrome (76076267067).

The spelling of 21025115055 in words is "twenty-one billion, twenty-five million, one hundred fifteen thousand, fifty-five".