21523156 has 24 divisors (see below), whose sum is σ = 40049856. Its totient is φ = 10085760.

The previous prime is 21523093. The next prime is 21523171. The reversal of 21523156 is 65132512.

It is a hoax number, since the sum of its digits (25) coincides with the sum of the digits of its distinct prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 21523156.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 20361 + ... + 21391.

It is an arithmetic number, because the mean of its divisors is an integer number (1668744).

Almost surely, 2^21523156 is an apocalyptic number.

It is an amenable number.

21523156 is a deficient number, since it is larger than the sum of its proper divisors (18526700).

21523156 is a wasteful number, since it uses less digits than its factorization.

21523156 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1359 (or 1357 counting only the distinct ones).

The product of its digits is 1800, while the sum is 25.

The square root of 21523156 is about 4639.3055514807. The cubic root of 21523156 is about 278.1646799591.

Adding to 21523156 its reverse (65132512), we get a palindrome (86655668).

The spelling of 21523156 in words is "twenty-one million, five hundred twenty-three thousand, one hundred fifty-six".