21244431 has 16 divisors (see below), whose sum is σ = 30877056. Its totient is φ = 12914016.

The previous prime is 21244417. The next prime is 21244459. The reversal of 21244431 is 13444212.

It is not a de Polignac number, because 21244431 - 2⁶ = 21244367 is a prime.

It is a super-2 number, since 2×21244431² = 902651697027522, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21244398 and 21244407.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21244481) 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, 45 + ... + 6518.

It is an arithmetic number, because the mean of its divisors is an integer number (1929816).

Almost surely, 2^21244431 is an apocalyptic number.

21244431 is a deficient number, since it is larger than the sum of its proper divisors (9632625).

21244431 is a wasteful number, since it uses less digits than its factorization.

21244431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6662.

The product of its digits is 768, while the sum is 21.

The square root of 21244431 is about 4609.1681462060. The cubic root of 21244431 is about 276.9587143654.

Adding to 21244431 its reverse (13444212), we get a palindrome (34688643).

It can be divided in two parts, 2124 and 4431, that added together give a triangular number (6555 = T₁₁₄).

The spelling of 21244431 in words is "twenty-one million, two hundred forty-four thousand, four hundred thirty-one".