277891961 has 2 divisors, whose sum is σ = 277891962. Its totient is φ = 277891960.

The previous prime is 277891931. The next prime is 277891963. The reversal of 277891961 is 169198772.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 212605561 + 65286400 = 14581^2 + 8080^2 .

It is a cyclic number.

It is not a de Polignac number, because 277891961 - 2²² = 273697657 is a prime.

Together with 277891963, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (277891963) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 138945980 + 138945981.

It is an arithmetic number, because the mean of its divisors is an integer number (138945981).

Almost surely, 2^277891961 is an apocalyptic number.

It is an amenable number.

277891961 is a deficient number, since it is larger than the sum of its proper divisors (1).

277891961 is an equidigital number, since it uses as much as digits as its factorization.

277891961 is an evil number, because the sum of its binary digits is even.

The product of its digits is 381024, while the sum is 50.

The square root of 277891961 is about 16670.0918113848. The cubic root of 277891961 is about 652.5673303881.

The spelling of 277891961 in words is "two hundred seventy-seven million, eight hundred ninety-one thousand, nine hundred sixty-one".