21095657 has 16 divisors (see below), whose sum is σ = 24639552. Its totient is φ = 17848320.

The previous prime is 21095653. The next prime is 21095663. The reversal of 21095657 is 75659012.

It is a cyclic number.

It is not a de Polignac number, because 21095657 - 2² = 21095653 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21095653) 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, 17558 + ... + 18720.

It is an arithmetic number, because the mean of its divisors is an integer number (1539972).

Almost surely, 2^21095657 is an apocalyptic number.

It is an amenable number.

21095657 is a deficient number, since it is larger than the sum of its proper divisors (3543895).

21095657 is a wasteful number, since it uses less digits than its factorization.

21095657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1288.

The product of its (nonzero) digits is 18900, while the sum is 35.

The square root of 21095657 is about 4593.0008708904. Note that the first 3 decimals coincide. The cubic root of 21095657 is about 276.3106886041.

The spelling of 21095657 in words is "twenty-one million, ninety-five thousand, six hundred fifty-seven".