21012611255 has 4 divisors (see below), whose sum is σ = 25215133512. Its totient is φ = 16810089000.

The previous prime is 21012611251. The next prime is 21012611261. The reversal of 21012611255 is 55211621012.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21012611255 - 2² = 21012611251 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21012611251) 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, 2101261121 + ... + 2101261130.

It is an arithmetic number, because the mean of its divisors is an integer number (6303783378).

Almost surely, 2^21012611255 is an apocalyptic number.

21012611255 is a deficient number, since it is larger than the sum of its proper divisors (4202522257).

21012611255 is an equidigital number, since it uses as much as digits as its factorization.

21012611255 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4202522256.

The product of its (nonzero) digits is 1200, while the sum is 26.

The spelling of 21012611255 in words is "twenty-one billion, twelve million, six hundred eleven thousand, two hundred fifty-five".