21155252531 has 32 divisors (see below), whose sum is σ = 25589465088. Its totient is φ = 17105346720.

The previous prime is 21155252527. The next prime is 21155252533. The reversal of 21155252531 is 13525255112.

It is not a de Polignac number, because 21155252531 - 2² = 21155252527 is a prime.

It is a super-2 number, since 2×21155252531² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21155252533) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 5251340 + ... + 5255366.

It is an arithmetic number, because the mean of its divisors is an integer number (799670784).

Almost surely, 2^21155252531 is an apocalyptic number.

21155252531 is a deficient number, since it is larger than the sum of its proper divisors (4434212557).

21155252531 is a wasteful number, since it uses less digits than its factorization.

21155252531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4671.

The product of its digits is 15000, while the sum is 32.

The spelling of 21155252531 in words is "twenty-one billion, one hundred fifty-five million, two hundred fifty-two thousand, five hundred thirty-one".