77661901 has 2 divisors, whose sum is σ = 77661902. Its totient is φ = 77661900.

The previous prime is 77661893. The next prime is 77661919. The reversal of 77661901 is 10916677.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 72233001 + 5428900 = 8499^2 + 2330^2 .

It is a cyclic number.

It is not a de Polignac number, because 77661901 - 2³ = 77661893 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (77667901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38830950 + 38830951.

It is an arithmetic number, because the mean of its divisors is an integer number (38830951).

Almost surely, 2^77661901 is an apocalyptic number.

It is an amenable number.

77661901 is a deficient number, since it is larger than the sum of its proper divisors (1).

77661901 is an equidigital number, since it uses as much as digits as its factorization.

77661901 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 15876, while the sum is 37.

The square root of 77661901 is about 8812.5989923518. The cubic root of 77661901 is about 426.6476314614.

The spelling of 77661901 in words is "seventy-seven million, six hundred sixty-one thousand, nine hundred one".