21969375 has 20 divisors (see below), whose sum is σ = 36607032. Its totient is φ = 11716000.

The previous prime is 21969371. The next prime is 21969397. The reversal of 21969375 is 57396912.

It is not a de Polignac number, because 21969375 - 2² = 21969371 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21969371) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 3984 + ... + 7733.

Almost surely, 2^21969375 is an apocalyptic number.

21969375 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21969375 is a deficient number, since it is larger than the sum of its proper divisors (14637657).

21969375 is an equidigital number, since it uses as much as digits as its factorization.

21969375 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11740 (or 11725 counting only the distinct ones).

The product of its digits is 102060, while the sum is 42.

The square root of 21969375 is about 4687.1499869324. The cubic root of 21969375 is about 280.0738538177.

The spelling of 21969375 in words is "twenty-one million, nine hundred sixty-nine thousand, three hundred seventy-five".