21372905 has 8 divisors (see below), whose sum is σ = 25936200. Its totient is φ = 16905856.

The previous prime is 21372889. The next prime is 21372937. The reversal of 21372905 is 50927312.

It can be written as a sum of positive squares in 4 ways, for example, as 478864 + 20894041 = 692^2 + 4571^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21372905 - 2⁴ = 21372889 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 23570 + ... + 24459.

It is an arithmetic number, because the mean of its divisors is an integer number (3242025).

Almost surely, 2^21372905 is an apocalyptic number.

It is an amenable number.

21372905 is a deficient number, since it is larger than the sum of its proper divisors (4563295).

21372905 is an equidigital number, since it uses as much as digits as its factorization.

21372905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48123.

The product of its (nonzero) digits is 3780, while the sum is 29.

The square root of 21372905 is about 4623.0839274233. The cubic root of 21372905 is about 277.5158879522.

The spelling of 21372905 in words is "twenty-one million, three hundred seventy-two thousand, nine hundred five".