20211977 has 2 divisors, whose sum is σ = 20211978. Its totient is φ = 20211976.

The previous prime is 20211973. The next prime is 20212001. The reversal of 20211977 is 77911202.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14661241 + 5550736 = 3829^2 + 2356^2 .

It is a cyclic number.

It is not a de Polignac number, because 20211977 - 2² = 20211973 is a prime.

It is not a weakly prime, because it can be changed into another prime (20211973) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10105988 + 10105989.

It is an arithmetic number, because the mean of its divisors is an integer number (10105989).

Almost surely, 2^20211977 is an apocalyptic number.

It is an amenable number.

20211977 is a deficient number, since it is larger than the sum of its proper divisors (1).

20211977 is an equidigital number, since it uses as much as digits as its factorization.

20211977 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1764, while the sum is 29.

The square root of 20211977 is about 4495.7732371640. The cubic root of 20211977 is about 272.3973835769.

The spelling of 20211977 in words is "twenty million, two hundred eleven thousand, nine hundred seventy-seven".