21706057 has 16 divisors (see below), whose sum is σ = 23069952. Its totient is φ = 20401920.

The previous prime is 21706033. The next prime is 21706067. The reversal of 21706057 is 75060712.

It is a cyclic number.

It is not a de Polignac number, because 21706057 - 2¹¹ = 21704009 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21706067) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 192033 + ... + 192145.

It is an arithmetic number, because the mean of its divisors is an integer number (1441872).

Almost surely, 2^21706057 is an apocalyptic number.

It is an amenable number.

21706057 is a deficient number, since it is larger than the sum of its proper divisors (1363895).

21706057 is a wasteful number, since it uses less digits than its factorization.

21706057 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 288.

The product of its (nonzero) digits is 2940, while the sum is 28.

The square root of 21706057 is about 4658.9759604445. The cubic root of 21706057 is about 278.9503943530.

Adding to 21706057 its reverse (75060712), we get a palindrome (96766769).

The spelling of 21706057 in words is "twenty-one million, seven hundred six thousand, fifty-seven".