21057071 has 8 divisors (see below), whose sum is σ = 24249984. Its totient is φ = 17910360.

The previous prime is 21057061. The next prime is 21057083. The reversal of 21057071 is 17075012.

It is a happy number.

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 21057071 - 2⁶ = 21057007 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21057061) 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, 10565 + ... + 12398.

It is an arithmetic number, because the mean of its divisors is an integer number (3031248).

Almost surely, 2^21057071 is an apocalyptic number.

21057071 is a deficient number, since it is larger than the sum of its proper divisors (3192913).

21057071 is a wasteful number, since it uses less digits than its factorization.

21057071 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23101.

The product of its (nonzero) digits is 490, while the sum is 23.

The square root of 21057071 is about 4588.7984266036. The cubic root of 21057071 is about 276.1421194481.

The spelling of 21057071 in words is "twenty-one million, fifty-seven thousand, seventy-one".