21310623 has 24 divisors (see below), whose sum is σ = 31824000. Its totient is φ = 13734864.

The previous prime is 21310613. The next prime is 21310637. The reversal of 21310623 is 32601312.

It is not a de Polignac number, because 21310623 - 2⁴ = 21310607 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21310596 and 21310605.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21310603) 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 23 ways as a sum of consecutive naturals, for example, 35278 + ... + 35876.

It is an arithmetic number, because the mean of its divisors is an integer number (1326000).

Almost surely, 2^21310623 is an apocalyptic number.

21310623 is a deficient number, since it is larger than the sum of its proper divisors (10513377).

21310623 is a wasteful number, since it uses less digits than its factorization.

21310623 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 731 (or 728 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 18.

The square root of 21310623 is about 4616.3430331811. The cubic root of 21310623 is about 277.2460593866.

Adding to 21310623 its reverse (32601312), we get a palindrome (53911935).

The spelling of 21310623 in words is "twenty-one million, three hundred ten thousand, six hundred twenty-three".