20997501 has 16 divisors (see below), whose sum is σ = 32436864. Its totient is φ = 11833344.

The previous prime is 20997491. The next prime is 20997511. The reversal of 20997501 is 10579902.

It is an interprime number because it is at equal distance from previous prime (20997491) and next prime (20997511).

It is not a de Polignac number, because 20997501 - 2⁶ = 20997437 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20997511) 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, 5316 + ... + 8381.

It is an arithmetic number, because the mean of its divisors is an integer number (2027304).

Almost surely, 2^20997501 is an apocalyptic number.

20997501 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

20997501 is a deficient number, since it is larger than the sum of its proper divisors (11439363).

20997501 is a wasteful number, since it uses less digits than its factorization.

20997501 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13780.

The product of its (nonzero) digits is 5670, while the sum is 33.

The square root of 20997501 is about 4582.3030235898. The cubic root of 20997501 is about 275.8814734714.

The spelling of 20997501 in words is "twenty million, nine hundred ninety-seven thousand, five hundred one".