21727945 has 8 divisors (see below), whose sum is σ = 26100360. Its totient is φ = 17364480.

The previous prime is 21727913. The next prime is 21727961. The reversal of 21727945 is 54972712.

It can be written as a sum of positive squares in 4 ways, for example, as 2996361 + 18731584 = 1731^2 + 4328^2 .

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

It is not a de Polignac number, because 21727945 - 2⁵ = 21727913 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, 5625 + ... + 8665.

It is an arithmetic number, because the mean of its divisors is an integer number (3262545).

Almost surely, 2^21727945 is an apocalyptic number.

It is an amenable number.

21727945 is a deficient number, since it is larger than the sum of its proper divisors (4372415).

21727945 is a wasteful number, since it uses less digits than its factorization.

21727945 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4475.

The product of its digits is 35280, while the sum is 37.

The square root of 21727945 is about 4661.3243826192. The cubic root of 21727945 is about 279.0441257187.

The spelling of 21727945 in words is "twenty-one million, seven hundred twenty-seven thousand, nine hundred forty-five".