21623699 has 2 divisors, whose sum is σ = 21623700. Its totient is φ = 21623698.

The previous prime is 21623681. The next prime is 21623731. The reversal of 21623699 is 99632612.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21623699 - 2²⁴ = 4846483 is a prime.

It is not a weakly prime, because it can be changed into another prime (21623639) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10811849 + 10811850.

It is an arithmetic number, because the mean of its divisors is an integer number (10811850).

Almost surely, 2^21623699 is an apocalyptic number.

21623699 is a deficient number, since it is larger than the sum of its proper divisors (1).

21623699 is an equidigital number, since it uses as much as digits as its factorization.

21623699 is an evil number, because the sum of its binary digits is even.

The product of its digits is 34992, while the sum is 38.

The square root of 21623699 is about 4650.1289229440. The cubic root of 21623699 is about 278.5971455798.

It can be divided in two parts, 21623 and 699, that added together give a palindrome (22322).

The spelling of 21623699 in words is "twenty-one million, six hundred twenty-three thousand, six hundred ninety-nine".