21997825 has 12 divisors (see below), whose sum is σ = 27342000. Its totient is φ = 17556560.

The previous prime is 21997793. The next prime is 21997837. The reversal of 21997825 is 52879912.

It is not a de Polignac number, because 21997825 - 2⁵ = 21997793 is a prime.

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 11 ways as a sum of consecutive naturals, for example, 13926 + ... + 15424.

It is an arithmetic number, because the mean of its divisors is an integer number (2278500).

Almost surely, 2^21997825 is an apocalyptic number.

21997825 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21997825 is a deficient number, since it is larger than the sum of its proper divisors (5344175).

21997825 is a wasteful number, since it uses less digits than its factorization.

21997825 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2096 (or 2091 counting only the distinct ones).

The product of its digits is 90720, while the sum is 43.

The square root of 21997825 is about 4690.1838983136. The cubic root of 21997825 is about 280.1946987680.

It can be divided in two parts, 21997 and 825, that added together give a palindrome (22822).

The spelling of 21997825 in words is "twenty-one million, nine hundred ninety-seven thousand, eight hundred twenty-five".