21957073 has 4 divisors (see below), whose sum is σ = 21983668. Its totient is φ = 21930480.

The previous prime is 21957071. The next prime is 21957077. The reversal of 21957073 is 37075912.

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 7463824 + 14493249 = 2732^2 + 3807^2 .

It is a cyclic number.

It is not a de Polignac number, because 21957073 - 2¹ = 21957071 is a prime.

It is a super-2 number, since 2×21957073² = 964226109454658, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21957071) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12018 + ... + 13723.

It is an arithmetic number, because the mean of its divisors is an integer number (5495917).

Almost surely, 2^21957073 is an apocalyptic number.

It is an amenable number.

21957073 is a deficient number, since it is larger than the sum of its proper divisors (26595).

21957073 is an equidigital number, since it uses as much as digits as its factorization.

21957073 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26594.

The product of its (nonzero) digits is 13230, while the sum is 34.

The square root of 21957073 is about 4685.8374918471. The cubic root of 21957073 is about 280.0215672163.

The spelling of 21957073 in words is "twenty-one million, nine hundred fifty-seven thousand, seventy-three".