77501981 has 2 divisors, whose sum is σ = 77501982. Its totient is φ = 77501980.

The previous prime is 77501917. The next prime is 77501993. The reversal of 77501981 is 18910577.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 67798756 + 9703225 = 8234^2 + 3115^2 .

It is a cyclic number.

It is not a de Polignac number, because 77501981 - 2⁶ = 77501917 is a prime.

It is a super-2 number, since 2×77501981² = 12013114117848722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (77501911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38750990 + 38750991.

It is an arithmetic number, because the mean of its divisors is an integer number (38750991).

Almost surely, 2^77501981 is an apocalyptic number.

It is an amenable number.

77501981 is a deficient number, since it is larger than the sum of its proper divisors (1).

77501981 is an equidigital number, since it uses as much as digits as its factorization.

77501981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 17640, while the sum is 38.

The square root of 77501981 is about 8803.5209433499. The cubic root of 77501981 is about 426.3545818266.

The spelling of 77501981 in words is "seventy-seven million, five hundred one thousand, nine hundred eighty-one".