21525723 has 32 divisors (see below), whose sum is σ = 35251200. Its totient is φ = 12912768.

The previous prime is 21525719. The next prime is 21525733. The reversal of 21525723 is 32752512.

It is not a de Polignac number, because 21525723 - 2² = 21525719 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (21525703) 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 31 ways as a sum of consecutive naturals, for example, 9538 + ... + 11576.

It is an arithmetic number, because the mean of its divisors is an integer number (1101600).

Almost surely, 2^21525723 is an apocalyptic number.

21525723 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

21525723 is a deficient number, since it is larger than the sum of its proper divisors (13725477).

21525723 is a wasteful number, since it uses less digits than its factorization.

21525723 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2088 (or 2082 counting only the distinct ones).

The product of its digits is 4200, while the sum is 27.

The square root of 21525723 is about 4639.5822010177. The cubic root of 21525723 is about 278.1757381321.

It can be divided in two parts, 2152 and 5723, that added together give a triangular number (7875 = T₁₂₅).

The spelling of 21525723 in words is "twenty-one million, five hundred twenty-five thousand, seven hundred twenty-three".