20997520 has 20 divisors (see below), whose sum is σ = 48819420. Its totient is φ = 8398976.

The previous prime is 20997517. The next prime is 20997521. The reversal of 20997520 is 2579902.

It can be written as a sum of positive squares in 2 ways, for example, as 2985984 + 18011536 = 1728^2 + 4244^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20997521) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 131155 + ... + 131314.

It is an arithmetic number, because the mean of its divisors is an integer number (2440971).

Almost surely, 2^20997520 is an apocalyptic number.

20997520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20997520 is an abundant number, since it is smaller than the sum of its proper divisors (27821900).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20997520 is a wasteful number, since it uses less digits than its factorization.

20997520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 262482 (or 262476 counting only the distinct ones).

The product of its (nonzero) digits is 11340, while the sum is 34.

The square root of 20997520 is about 4582.3050967826. The cubic root of 20997520 is about 275.8815566836.

The spelling of 20997520 in words is "twenty million, nine hundred ninety-seven thousand, five hundred twenty".