20977 has 4 divisors (see below), whose sum is σ = 22896. Its totient is φ = 19060.

The previous prime is 20963. The next prime is 20981. The reversal of 20977 is 77902.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20977 - 2⁷ = 20849 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20947) 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, 943 + ... + 964.

It is an arithmetic number, because the mean of its divisors is an integer number (5724).

2²⁰⁹⁷⁷ is an apocalyptic number.

It is an amenable number.

20977 is a deficient number, since it is larger than the sum of its proper divisors (1919).

20977 is a wasteful number, since it uses less digits than its factorization.

20977 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1918.

The product of its (nonzero) digits is 882, while the sum is 25.

The square root of 20977 is about 144.8343881818. The cubic root of 20977 is about 27.5791658215.

Multiplying 20977 by its sum of digits (25), we get a palindrome (524425).

The spelling of 20977 in words is "twenty thousand, nine hundred seventy-seven".