21453831 has 24 divisors (see below), whose sum is σ = 37281920. Its totient is φ = 11613456.

The previous prime is 21453799. The next prime is 21453833. The reversal of 21453831 is 13835412.

It is a happy number.

It is not a de Polignac number, because 21453831 - 2⁵ = 21453799 is a prime.

It is a super-2 number, since 2×21453831² = 920533729153122, 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 = 21453795 and 21453804.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21453833) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7765 + ... + 10158.

Almost surely, 2^21453831 is an apocalyptic number.

21453831 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21453831 is a deficient number, since it is larger than the sum of its proper divisors (15828089).

21453831 is a wasteful number, since it uses less digits than its factorization.

21453831 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17955 (or 17952 counting only the distinct ones).

The product of its digits is 2880, while the sum is 27.

The square root of 21453831 is about 4631.8280408495. The cubic root of 21453831 is about 277.8657072685.

It can be divided in two parts, 214 and 53831, that added together give a palindrome (54045).

The spelling of 21453831 in words is "twenty-one million, four hundred fifty-three thousand, eight hundred thirty-one".