21012431 has 16 divisors (see below), whose sum is σ = 23708160. Its totient is φ = 18458880.

The previous prime is 21012421. The next prime is 21012449. The reversal of 21012431 is 13421012.

It is not a de Polignac number, because 21012431 - 2⁶ = 21012367 is a prime.

It is a super-2 number, since 2×21012431² = 883044513059522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21012401) 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, 49940 + ... + 50358.

It is an arithmetic number, because the mean of its divisors is an integer number (1481760).

Almost surely, 2^21012431 is an apocalyptic number.

21012431 is a deficient number, since it is larger than the sum of its proper divisors (2695729).

21012431 is a wasteful number, since it uses less digits than its factorization.

21012431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 574.

The product of its (nonzero) digits is 48, while the sum is 14.

The square root of 21012431 is about 4583.9318275908. The cubic root of 21012431 is about 275.9468452912.

Adding to 21012431 its reverse (13421012), we get a palindrome (34433443).

The spelling of 21012431 in words is "twenty-one million, twelve thousand, four hundred thirty-one".