21552523 has 4 divisors (see below), whose sum is σ = 21917880. Its totient is φ = 21187168.

The previous prime is 21552521. The next prime is 21552529. The reversal of 21552523 is 32525512.

It is a happy number.

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 21552523 - 2¹ = 21552521 is a prime.

It is a super-2 number, since 2×21552523² = 929022495331058, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21552521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 182590 + ... + 182707.

It is an arithmetic number, because the mean of its divisors is an integer number (5479470).

Almost surely, 2^21552523 is an apocalyptic number.

21552523 is a deficient number, since it is larger than the sum of its proper divisors (365357).

21552523 is an equidigital number, since it uses as much as digits as its factorization.

21552523 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 365356.

The product of its digits is 3000, while the sum is 25.

The square root of 21552523 is about 4642.4694937070. The cubic root of 21552523 is about 278.2911352316.

The spelling of 21552523 in words is "twenty-one million, five hundred fifty-two thousand, five hundred twenty-three".