21031023 has 16 divisors (see below), whose sum is σ = 31975776. Its totient is φ = 12180480.

The previous prime is 21031019. The next prime is 21031027. The reversal of 21031023 is 32013012.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21031019) and next prime (21031027).

It is not a de Polignac number, because 21031023 - 2² = 21031019 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21031027) 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, 15198 + ... + 16523.

It is an arithmetic number, because the mean of its divisors is an integer number (1998486).

Almost surely, 2^21031023 is an apocalyptic number.

21031023 is a deficient number, since it is larger than the sum of its proper divisors (10944753).

21031023 is a wasteful number, since it uses less digits than its factorization.

21031023 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31754.

The product of its (nonzero) digits is 36, while the sum is 12.

The square root of 21031023 is about 4585.9593325715. The cubic root of 21031023 is about 276.0282081020.

Adding to 21031023 its reverse (32013012), we get a palindrome (53044035).

The spelling of 21031023 in words is "twenty-one million, thirty-one thousand, twenty-three".