21893831 has 2 divisors, whose sum is σ = 21893832. Its totient is φ = 21893830.

The previous prime is 21893827. The next prime is 21893887. The reversal of 21893831 is 13839812.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21893831 - 2² = 21893827 is a prime.

It is a super-2 number, since 2×21893831² = 958679671713122, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21893791 and 21893800.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21893891) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10946915 + 10946916.

It is an arithmetic number, because the mean of its divisors is an integer number (10946916).

Almost surely, 2^21893831 is an apocalyptic number.

21893831 is a deficient number, since it is larger than the sum of its proper divisors (1).

21893831 is an equidigital number, since it uses as much as digits as its factorization.

21893831 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10368, while the sum is 35.

The square root of 21893831 is about 4679.0844189863. The cubic root of 21893831 is about 279.7524640517.

It can be divided in two parts, 218 and 93831, that added together give a palindrome (94049).

The spelling of 21893831 in words is "twenty-one million, eight hundred ninety-three thousand, eight hundred thirty-one".