20897567 has 4 divisors (see below), whose sum is σ = 21100560. Its totient is φ = 20694576.

The previous prime is 20897561. The next prime is 20897579. The reversal of 20897567 is 76579802.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20897567 - 2⁴ = 20897551 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20897561) 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, 101342 + ... + 101547.

It is an arithmetic number, because the mean of its divisors is an integer number (5275140).

Almost surely, 2^20897567 is an apocalyptic number.

20897567 is a deficient number, since it is larger than the sum of its proper divisors (202993).

20897567 is a wasteful number, since it uses less digits than its factorization.

20897567 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 202992.

The product of its (nonzero) digits is 211680, while the sum is 44.

The square root of 20897567 is about 4571.3856761380. The cubic root of 20897567 is about 275.4431071262.

The spelling of 20897567 in words is "twenty million, eight hundred ninety-seven thousand, five hundred sixty-seven".