21155252031 has 10 divisors (see below), whose sum is σ = 31602290192. Its totient is φ = 14103501300.

The previous prime is 21155252011. The next prime is 21155252033. The reversal of 21155252031 is 13025255112.

21155252031 is a `hidden beast` number, since 2 + 115 + 525 + 20 + 3 + 1 = 666.

It is not a de Polignac number, because 21155252031 - 2⁶ = 21155251967 is a prime.

It is a super-2 number, since 2×21155252031² (a number of 21 digits) contains 22 as substring.

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

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21155251986 and 21155252004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21155252033) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 130587895 + ... + 130588056.

Almost surely, 2^21155252031 is an apocalyptic number.

21155252031 is a deficient number, since it is larger than the sum of its proper divisors (10447038161).

21155252031 is an equidigital number, since it uses as much as digits as its factorization.

21155252031 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 261175963 (or 261175954 counting only the distinct ones).

The product of its (nonzero) digits is 3000, while the sum is 27.

The spelling of 21155252031 in words is "twenty-one billion, one hundred fifty-five million, two hundred fifty-two thousand, thirty-one".