21404657 has 8 divisors (see below), whose sum is σ = 21700800. Its totient is φ = 21110544.

The previous prime is 21404653. The next prime is 21404681. The reversal of 21404657 is 75640412.

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 21404657 - 2² = 21404653 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21404653) 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, 38858 + ... + 39404.

It is an arithmetic number, because the mean of its divisors is an integer number (2712600).

Almost surely, 2^21404657 is an apocalyptic number.

It is an amenable number.

21404657 is a deficient number, since it is larger than the sum of its proper divisors (296143).

21404657 is a wasteful number, since it uses less digits than its factorization.

21404657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1015.

The product of its (nonzero) digits is 6720, while the sum is 29.

The square root of 21404657 is about 4626.5167242754. The cubic root of 21404657 is about 277.6532476056.

The spelling of 21404657 in words is "twenty-one million, four hundred four thousand, six hundred fifty-seven".