21753623 has 2 divisors, whose sum is σ = 21753624. Its totient is φ = 21753622.

The previous prime is 21753583. The next prime is 21753629. The reversal of 21753623 is 32635712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21753623 - 2⁶ = 21753559 is a prime.

It is a super-2 number, since 2×21753623² = 946440227252258, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21753629) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10876811 + 10876812.

It is an arithmetic number, because the mean of its divisors is an integer number (10876812).

Almost surely, 2^21753623 is an apocalyptic number.

21753623 is a deficient number, since it is larger than the sum of its proper divisors (1).

21753623 is an equidigital number, since it uses as much as digits as its factorization.

21753623 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7560, while the sum is 29.

The square root of 21753623 is about 4664.0779367416. The cubic root of 21753623 is about 279.1540068614.

The spelling of 21753623 in words is "twenty-one million, seven hundred fifty-three thousand, six hundred twenty-three".