20997495 has 16 divisors (see below), whose sum is σ = 37329120. Its totient is φ = 11198592.

The previous prime is 20997491. The next prime is 20997511. The reversal of 20997495 is 59479902.

It is not a de Polignac number, because 20997495 - 2² = 20997491 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 20997495.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20997491) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 77634 + ... + 77903.

It is an arithmetic number, because the mean of its divisors is an integer number (2333070).

Almost surely, 2^20997495 is an apocalyptic number.

20997495 is a deficient number, since it is larger than the sum of its proper divisors (16331625).

20997495 is a wasteful number, since it uses less digits than its factorization.

20997495 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 155551 (or 155545 counting only the distinct ones).

The product of its (nonzero) digits is 204120, while the sum is 45.

The square root of 20997495 is about 4582.3023688971. The cubic root of 20997495 is about 275.8814471939.

The spelling of 20997495 in words is "twenty million, nine hundred ninety-seven thousand, four hundred ninety-five".