21323031 has 4 divisors (see below), whose sum is σ = 28430712. Its totient is φ = 14215352.

The previous prime is 21323021. The next prime is 21323053. The reversal of 21323031 is 13032312.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21323031 - 2⁵ = 21322999 is a prime.

It is a super-2 number, since 2×21323031² = 909343302053922, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21323031.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21323011) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3553836 + ... + 3553841.

It is an arithmetic number, because the mean of its divisors is an integer number (7107678).

Almost surely, 2^21323031 is an apocalyptic number.

21323031 is a deficient number, since it is larger than the sum of its proper divisors (7107681).

21323031 is an equidigital number, since it uses as much as digits as its factorization.

21323031 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7107680.

The product of its (nonzero) digits is 108, while the sum is 15.

The square root of 21323031 is about 4617.6867585405. The cubic root of 21323031 is about 277.2998573080.

Adding to 21323031 its reverse (13032312), we get a palindrome (34355343).

The spelling of 21323031 in words is "twenty-one million, three hundred twenty-three thousand, thirty-one".