21038623 has 4 divisors (see below), whose sum is σ = 21190120. Its totient is φ = 20887128.

The previous prime is 21038609. The next prime is 21038627. The reversal of 21038623 is 32683012.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21038623 is a prime.

It is a super-2 number, since 2×21038623² = 885247315472258, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21038627) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 75540 + ... + 75817.

It is an arithmetic number, because the mean of its divisors is an integer number (5297530).

Almost surely, 2^21038623 is an apocalyptic number.

21038623 is a deficient number, since it is larger than the sum of its proper divisors (151497).

21038623 is a wasteful number, since it uses less digits than its factorization.

21038623 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 151496.

The product of its (nonzero) digits is 1728, while the sum is 25.

The square root of 21038623 is about 4586.7878738830. The cubic root of 21038623 is about 276.0614536196.

The spelling of 21038623 in words is "twenty-one million, thirty-eight thousand, six hundred twenty-three".