21927505 has 4 divisors (see below), whose sum is σ = 26313012. Its totient is φ = 17542000.

The previous prime is 21927481. The next prime is 21927511. The reversal of 21927505 is 50572912.

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

It can be written as a sum of positive squares in 2 ways, for example, as 2461761 + 19465744 = 1569^2 + 4412^2 .

It is not a de Polignac number, because 21927505 - 2¹⁵ = 21894737 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2192746 + ... + 2192755.

It is an arithmetic number, because the mean of its divisors is an integer number (6578253).

Almost surely, 2^21927505 is an apocalyptic number.

It is an amenable number.

21927505 is a deficient number, since it is larger than the sum of its proper divisors (4385507).

21927505 is an equidigital number, since it uses as much as digits as its factorization.

21927505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4385506.

The product of its (nonzero) digits is 6300, while the sum is 31.

The square root of 21927505 is about 4682.6813899731. The cubic root of 21927505 is about 279.8958158311.

The spelling of 21927505 in words is "twenty-one million, nine hundred twenty-seven thousand, five hundred five".