21550523 has 4 divisors (see below), whose sum is σ = 21571368. Its totient is φ = 21529680.

The previous prime is 21550519. The next prime is 21550537. The reversal of 21550523 is 32505512.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21550523 - 2² = 21550519 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21550513) 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, 8786 + ... + 10967.

It is an arithmetic number, because the mean of its divisors is an integer number (5392842).

Almost surely, 2^21550523 is an apocalyptic number.

21550523 is a deficient number, since it is larger than the sum of its proper divisors (20845).

21550523 is a wasteful number, since it uses less digits than its factorization.

21550523 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20844.

The product of its (nonzero) digits is 1500, while the sum is 23.

The square root of 21550523 is about 4642.2540861095. The cubic root of 21550523 is about 278.2825268119.

The spelling of 21550523 in words is "twenty-one million, five hundred fifty thousand, five hundred twenty-three".