21553771 has 8 divisors (see below), whose sum is σ = 22738320. Its totient is φ = 20374272.

The previous prime is 21553717. The next prime is 21553787. The reversal of 21553771 is 17735512.

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 21553771 - 2⁷ = 21553643 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21593771) 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, 10311 + ... + 12223.

It is an arithmetic number, because the mean of its divisors is an integer number (2842290).

Almost surely, 2^21553771 is an apocalyptic number.

21553771 is a deficient number, since it is larger than the sum of its proper divisors (1184549).

21553771 is a wasteful number, since it uses less digits than its factorization.

21553771 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2525.

The product of its digits is 7350, while the sum is 31.

The square root of 21553771 is about 4642.6039029838. The cubic root of 21553771 is about 278.2965066156.

The spelling of 21553771 in words is "twenty-one million, five hundred fifty-three thousand, seven hundred seventy-one".