21672331 has 16 divisors (see below), whose sum is σ = 24343200. Its totient is φ = 19173888.

The previous prime is 21672323. The next prime is 21672337. The reversal of 21672331 is 13327612.

It is not a de Polignac number, because 21672331 - 2³ = 21672323 is a prime.

It is a super-2 number, since 2×21672331² = 939379861947122, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21672296 and 21672305.

It is not an unprimeable number, because it can be changed into a prime (21672337) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 73821 + ... + 74113.

It is an arithmetic number, because the mean of its divisors is an integer number (1521450).

Almost surely, 2^21672331 is an apocalyptic number.

21672331 is a deficient number, since it is larger than the sum of its proper divisors (2670869).

21672331 is a wasteful number, since it uses less digits than its factorization.

21672331 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 558.

The product of its digits is 1512, while the sum is 25.

The square root of 21672331 is about 4655.3550884975. The cubic root of 21672331 is about 278.8058454875.

Adding to 21672331 its reverse (13327612), we get a palindrome (34999943).

The spelling of 21672331 in words is "twenty-one million, six hundred seventy-two thousand, three hundred thirty-one".