21557071 has 8 divisors (see below), whose sum is σ = 22879584. Its totient is φ = 20240640.

The previous prime is 21557057. The next prime is 21557099. The reversal of 21557071 is 17075512.

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 21557071 - 2⁷ = 21556943 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 (21557671) 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, 7291 + ... + 9811.

It is an arithmetic number, because the mean of its divisors is an integer number (2859948).

Almost surely, 2^21557071 is an apocalyptic number.

21557071 is a deficient number, since it is larger than the sum of its proper divisors (1322513).

21557071 is a wasteful number, since it uses less digits than its factorization.

21557071 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3041.

The product of its (nonzero) digits is 2450, while the sum is 28.

The square root of 21557071 is about 4642.9592933818. The cubic root of 21557071 is about 278.3107087956.

The spelling of 21557071 in words is "twenty-one million, five hundred fifty-seven thousand, seventy-one".