21872331 has 24 divisors (see below), whose sum is σ = 34515936. Its totient is φ = 13265280.

The previous prime is 21872317. The next prime is 21872341. The reversal of 21872331 is 13327812.

It is not a de Polignac number, because 21872331 - 2⁷ = 21872203 is a prime.

It is a super-2 number, since 2×21872331² = 956797726747122, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21872295 and 21872304.

It is not an unprimeable number, because it can be changed into a prime (21872341) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 6991 + ... + 9623.

It is an arithmetic number, because the mean of its divisors is an integer number (1438164).

Almost surely, 2^21872331 is an apocalyptic number.

21872331 is a deficient number, since it is larger than the sum of its proper divisors (12643605).

21872331 is a wasteful number, since it uses less digits than its factorization.

21872331 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2723 (or 2720 counting only the distinct ones).

The product of its digits is 2016, while the sum is 27.

The square root of 21872331 is about 4676.7863966617. The cubic root of 21872331 is about 279.6608606547.

The spelling of 21872331 in words is "twenty-one million, eight hundred seventy-two thousand, three hundred thirty-one".