21251500231 has 4 divisors (see below), whose sum is σ = 22886231032. Its totient is φ = 19616769432.

The previous prime is 21251500223. The next prime is 21251500241. The reversal of 21251500231 is 13200515212.

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

It is not a de Polignac number, because 21251500231 - 2³ = 21251500223 is a prime.

It is a super-2 number, since 2×21251500231² (a number of 21 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 (21251500201) 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, 817365381 + ... + 817365406.

It is an arithmetic number, because the mean of its divisors is an integer number (5721557758).

Almost surely, 2^21251500231 is an apocalyptic number.

21251500231 is a deficient number, since it is larger than the sum of its proper divisors (1634730801).

21251500231 is a wasteful number, since it uses less digits than its factorization.

21251500231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1634730800.

The product of its (nonzero) digits is 600, while the sum is 22.

The spelling of 21251500231 in words is "twenty-one billion, two hundred fifty-one million, five hundred thousand, two hundred thirty-one".