137777561 has 2 divisors, whose sum is σ = 137777562. Its totient is φ = 137777560.

The previous prime is 137777557. The next prime is 137777573. The reversal of 137777561 is 165777731.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 103144336 + 34633225 = 10156^2 + 5885^2 .

It is a cyclic number.

It is not a de Polignac number, because 137777561 - 2² = 137777557 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is equal to p_7793729 and since 137777561 and 7793729 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (137779561) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 68888780 + 68888781.

It is an arithmetic number, because the mean of its divisors is an integer number (68888781).

Almost surely, 2^137777561 is an apocalyptic number.

It is an amenable number.

137777561 is a deficient number, since it is larger than the sum of its proper divisors (1).

137777561 is an equidigital number, since it uses as much as digits as its factorization.

137777561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 216090, while the sum is 44.

The square root of 137777561 is about 11737.8686736562. The cubic root of 137777561 is about 516.4871221214.

The spelling of 137777561 in words is "one hundred thirty-seven million, seven hundred seventy-seven thousand, five hundred sixty-one".