21761623 has 6 divisors (see below), whose sum is σ = 23564544. Its totient is φ = 20087496.

The previous prime is 21761617. The next prime is 21761627. The reversal of 21761623 is 32616712.

It is not a de Polignac number, because 21761623 - 2¹⁷ = 21630551 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21761591 and 21761600.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21761627) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 64215 + ... + 64552.

It is an arithmetic number, because the mean of its divisors is an integer number (3927424).

Almost surely, 2^21761623 is an apocalyptic number.

21761623 is a deficient number, since it is larger than the sum of its proper divisors (1802921).

21761623 is a wasteful number, since it uses less digits than its factorization.

21761623 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 128793 (or 128780 counting only the distinct ones).

The product of its digits is 3024, while the sum is 28.

The square root of 21761623 is about 4664.9354765098. The cubic root of 21761623 is about 279.1882227458.

The spelling of 21761623 in words is "twenty-one million, seven hundred sixty-one thousand, six hundred twenty-three".