21401657 has 16 divisors (see below), whose sum is σ = 24053760. Its totient is φ = 18922752.

The previous prime is 21401647. The next prime is 21401663. The reversal of 21401657 is 75610412.

It is a cyclic number.

It is not a de Polignac number, because 21401657 - 2⁴ = 21401641 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21401617) 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, 55688 + ... + 56070.

It is an arithmetic number, because the mean of its divisors is an integer number (1503360).

Almost surely, 2^21401657 is an apocalyptic number.

It is an amenable number.

21401657 is a deficient number, since it is larger than the sum of its proper divisors (2652103).

21401657 is a wasteful number, since it uses less digits than its factorization.

21401657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 592.

The product of its (nonzero) digits is 1680, while the sum is 26.

The square root of 21401657 is about 4626.1924949141. The cubic root of 21401657 is about 277.6402753715.

The spelling of 21401657 in words is "twenty-one million, four hundred one thousand, six hundred fifty-seven".