20985977 has 4 divisors (see below), whose sum is σ = 21662976. Its totient is φ = 20308980.

The previous prime is 20985971. The next prime is 20985983. The reversal of 20985977 is 77958902.

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 an interprime number because it is at equal distance from previous prime (20985971) and next prime (20985983).

It is a cyclic number.

It is not a de Polignac number, because 20985977 - 2⁴ = 20985961 is a prime.

It is a super-2 number, since 2×20985977² = 880822461289058, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20985971) 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, 338453 + ... + 338514.

It is an arithmetic number, because the mean of its divisors is an integer number (5415744).

Almost surely, 2^20985977 is an apocalyptic number.

It is an amenable number.

20985977 is a deficient number, since it is larger than the sum of its proper divisors (676999).

20985977 is an equidigital number, since it uses as much as digits as its factorization.

20985977 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 676998.

The product of its (nonzero) digits is 317520, while the sum is 47.

The square root of 20985977 is about 4581.0454047084. The cubic root of 20985977 is about 275.8309938151.

The spelling of 20985977 in words is "twenty million, nine hundred eighty-five thousand, nine hundred seventy-seven".