20997975 has 48 divisors (see below), whose sum is σ = 37711872. Its totient is φ = 10268160.

The previous prime is 20997973. The next prime is 20997989. The reversal of 20997975 is 57979902.

It is not a de Polignac number, because 20997975 - 2¹ = 20997973 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20997971) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 54634 + ... + 55016.

It is an arithmetic number, because the mean of its divisors is an integer number (785664).

Almost surely, 2^20997975 is an apocalyptic number.

20997975 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

20997975 is a deficient number, since it is larger than the sum of its proper divisors (16713897).

20997975 is a wasteful number, since it uses less digits than its factorization.

20997975 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 456 (or 451 counting only the distinct ones).

The product of its (nonzero) digits is 357210, while the sum is 48.

The square root of 20997975 is about 4582.3547440154. The cubic root of 20997975 is about 275.8835493825.

The spelling of 20997975 in words is "twenty million, nine hundred ninety-seven thousand, nine hundred seventy-five".