21231436 has 24 divisors (see below), whose sum is σ = 41413680. Its totient is φ = 9464832.

The previous prime is 21231433. The next prime is 21231439. The reversal of 21231436 is 63413212.

It is an interprime number because it is at equal distance from previous prime (21231433) and next prime (21231439).

It is not an unprimeable number, because it can be changed into a prime (21231433) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6925 + ... + 9508.

It is an arithmetic number, because the mean of its divisors is an integer number (1725570).

Almost surely, 2^21231436 is an apocalyptic number.

It is an amenable number.

21231436 is a deficient number, since it is larger than the sum of its proper divisors (20182244).

21231436 is a wasteful number, since it uses less digits than its factorization.

21231436 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16473 (or 16471 counting only the distinct ones).

The product of its digits is 864, while the sum is 22.

The square root of 21231436 is about 4607.7582401858. The cubic root of 21231436 is about 276.9022319147.

Adding to 21231436 its reverse (63413212), we get a palindrome (84644648).

The spelling of 21231436 in words is "twenty-one million, two hundred thirty-one thousand, four hundred thirty-six".