21766457 has 8 divisors (see below), whose sum is σ = 23301600. Its totient is φ = 20270304.

The previous prime is 21766439. The next prime is 21766513. The reversal of 21766457 is 75466712.

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 21766457 - 2¹⁴ = 21750073 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21766457.

It is not an unprimeable number, because it can be changed into a prime (21766057) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8588 + ... + 10829.

It is an arithmetic number, because the mean of its divisors is an integer number (2912700).

Almost surely, 2^21766457 is an apocalyptic number.

It is an amenable number.

21766457 is a deficient number, since it is larger than the sum of its proper divisors (1535143).

21766457 is a wasteful number, since it uses less digits than its factorization.

21766457 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19495.

The product of its digits is 70560, while the sum is 38.

The square root of 21766457 is about 4665.4535685183. The cubic root of 21766457 is about 279.2088936297.

The spelling of 21766457 in words is "twenty-one million, seven hundred sixty-six thousand, four hundred fifty-seven".