21625899 has 8 divisors (see below), whose sum is σ = 29182272. Its totient is φ = 14243400.

The previous prime is 21625889. The next prime is 21625913. The reversal of 21625899 is 99852612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21625899 - 2⁷ = 21625771 is a prime.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a self number, because there is not a number n which added to its sum of digits gives 21625899.

It is not an unprimeable number, because it can be changed into a prime (21625889) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 43177 + ... + 43674.

It is an arithmetic number, because the mean of its divisors is an integer number (3647784).

Almost surely, 2^21625899 is an apocalyptic number.

21625899 is a deficient number, since it is larger than the sum of its proper divisors (7556373).

21625899 is an equidigital number, since it uses as much as digits as its factorization.

21625899 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 86937.

The product of its digits is 77760, while the sum is 42.

The square root of 21625899 is about 4650.3654695088. The cubic root of 21625899 is about 278.6065934382.

The spelling of 21625899 in words is "twenty-one million, six hundred twenty-five thousand, eight hundred ninety-nine".