21988125 has 40 divisors (see below), whose sum is σ = 40736960. Its totient is φ = 11718000.

The previous prime is 21988103. The next prime is 21988133. The reversal of 21988125 is 52188912.

It is not a de Polignac number, because 21988125 - 2¹¹ = 21986077 is a prime.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 21988125.

It is a congruent number.

It is an unprimeable number.

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 39 ways as a sum of consecutive naturals, for example, 16224 + ... + 17526.

It is an arithmetic number, because the mean of its divisors is an integer number (1018424).

Almost surely, 2^21988125 is an apocalyptic number.

21988125 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21988125 is a deficient number, since it is larger than the sum of its proper divisors (18748835).

21988125 is an equidigital number, since it uses as much as digits as its factorization.

21988125 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1332 (or 1311 counting only the distinct ones).

The product of its digits is 11520, while the sum is 36.

The square root of 21988125 is about 4689.1497097022. The cubic root of 21988125 is about 280.1535085115.

The spelling of 21988125 in words is "twenty-one million, nine hundred eighty-eight thousand, one hundred twenty-five".