21550757 has 4 divisors (see below), whose sum is σ = 21720576. Its totient is φ = 21380940.

The previous prime is 21550691. The next prime is 21550777. The reversal of 21550757 is 75705512.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21550757 - 2¹⁶ = 21485221 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 (21550777) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 84719 + ... + 84972.

It is an arithmetic number, because the mean of its divisors is an integer number (5430144).

Almost surely, 2^21550757 is an apocalyptic number.

It is an amenable number.

21550757 is a deficient number, since it is larger than the sum of its proper divisors (169819).

21550757 is a wasteful number, since it uses less digits than its factorization.

21550757 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 169818.

The product of its (nonzero) digits is 12250, while the sum is 32.

The square root of 21550757 is about 4642.2792893147. The cubic root of 21550757 is about 278.2835340245.

The spelling of 21550757 in words is "twenty-one million, five hundred fifty thousand, seven hundred fifty-seven".