21412531 has 4 divisors (see below), whose sum is σ = 24471472. Its totient is φ = 18353592.

The previous prime is 21412513. The next prime is 21412549. The reversal of 21412531 is 13521412.

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

It is an interprime number because it is at equal distance from previous prime (21412513) and next prime (21412549).

It is a cyclic number.

It is not a de Polignac number, because 21412531 - 2⁵ = 21412499 is a prime.

It is a super-2 number, since 2×21412531² = 916992967651922, 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 = 21412499 and 21412508.

It is not an unprimeable number, because it can be changed into a prime (21412561) 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, 1529460 + ... + 1529473.

It is an arithmetic number, because the mean of its divisors is an integer number (6117868).

Almost surely, 2^21412531 is an apocalyptic number.

21412531 is a deficient number, since it is larger than the sum of its proper divisors (3058941).

21412531 is an equidigital number, since it uses as much as digits as its factorization.

21412531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3058940.

The product of its digits is 240, while the sum is 19.

The square root of 21412531 is about 4627.3676102078. The cubic root of 21412531 is about 277.6872896312.

Adding to 21412531 its reverse (13521412), we get a palindrome (34933943).

The spelling of 21412531 in words is "twenty-one million, four hundred twelve thousand, five hundred thirty-one".