21472331 has 4 divisors (see below), whose sum is σ = 21503664. Its totient is φ = 21441000.

The previous prime is 21472313. The next prime is 21472379. The reversal of 21472331 is 13327412.

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 21472331 - 2¹⁴ = 21455947 is a prime.

It is a super-2 number, since 2×21472331² = 922121997147122, 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 = 21472297 and 21472306.

It is not an unprimeable number, because it can be changed into a prime (21472391) 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, 14615 + ... + 16016.

It is an arithmetic number, because the mean of its divisors is an integer number (5375916).

Almost surely, 2^21472331 is an apocalyptic number.

21472331 is a deficient number, since it is larger than the sum of its proper divisors (31333).

21472331 is an equidigital number, since it uses as much as digits as its factorization.

21472331 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31332.

The product of its digits is 1008, while the sum is 23.

The square root of 21472331 is about 4633.8246621986. The cubic root of 21472331 is about 277.9455537492.

Adding to 21472331 its reverse (13327412), we get a palindrome (34799743).

The spelling of 21472331 in words is "twenty-one million, four hundred seventy-two thousand, three hundred thirty-one".