21155164252031 has 4 divisors (see below), whose sum is σ = 21155322651000. Its totient is φ = 21155005853064.

The previous prime is 21155164252009. The next prime is 21155164252067. The reversal of 21155164252031 is 13025246155112.

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

It is a cyclic number.

It is not a de Polignac number, because 21155164252031 - 2⁶ = 21155164251967 is a prime.

It is a super-2 number, since 2×21155164252031² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21155164252091) 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, 78998981 + ... + 79266318.

It is an arithmetic number, because the mean of its divisors is an integer number (5288830662750).

Almost surely, 2^{21155164252031} is an apocalyptic number.

21155164252031 is a deficient number, since it is larger than the sum of its proper divisors (158398969).

21155164252031 is a wasteful number, since it uses less digits than its factorization.

21155164252031 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 158398968.

The product of its (nonzero) digits is 72000, while the sum is 38.

The spelling of 21155164252031 in words is "twenty-one trillion, one hundred fifty-five billion, one hundred sixty-four million, two hundred fifty-two thousand, thirty-one".