21525805 has 16 divisors (see below), whose sum is σ = 29723904. Its totient is φ = 14659200.

The previous prime is 21525793. The next prime is 21525853. The reversal of 21525805 is 50852512.

It is not a de Polignac number, because 21525805 - 2⁵ = 21525773 is a prime.

It is a super-3 number, since 3×21525805³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3249 + ... + 7321.

It is an arithmetic number, because the mean of its divisors is an integer number (1857744).

Almost surely, 2^21525805 is an apocalyptic number.

It is an amenable number.

21525805 is a deficient number, since it is larger than the sum of its proper divisors (8198099).

21525805 is a wasteful number, since it uses less digits than its factorization.

21525805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4236.

The product of its (nonzero) digits is 4000, while the sum is 28.

The square root of 21525805 is about 4639.5910380119. The cubic root of 21525805 is about 278.1760913588.

The spelling of 21525805 in words is "twenty-one million, five hundred twenty-five thousand, eight hundred five".