21623825 has 6 divisors (see below), whose sum is σ = 26813574. Its totient is φ = 17299040.

The previous prime is 21623809. The next prime is 21623827. The reversal of 21623825 is 52832612.

It can be written as a sum of positive squares in 3 ways, for example, as 2193361 + 19430464 = 1481^2 + 4408^2 .

It is not a de Polignac number, because 21623825 - 2⁴ = 21623809 is a prime.

It is a super-3 number, since 3×21623825³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21623827) by changing a digit.

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 5 ways as a sum of consecutive naturals, for example, 432452 + ... + 432501.

It is an arithmetic number, because the mean of its divisors is an integer number (4468929).

Almost surely, 2^21623825 is an apocalyptic number.

21623825 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21623825 is a deficient number, since it is larger than the sum of its proper divisors (5189749).

21623825 is an equidigital number, since it uses as much as digits as its factorization.

21623825 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 864963 (or 864958 counting only the distinct ones).

The product of its digits is 5760, while the sum is 29.

The square root of 21623825 is about 4650.1424709357. The cubic root of 21623825 is about 278.5976867018.

The spelling of 21623825 in words is "twenty-one million, six hundred twenty-three thousand, eight hundred twenty-five".