77211661 has 2 divisors, whose sum is σ = 77211662. Its totient is φ = 77211660.

The previous prime is 77211643. The next prime is 77211689. The reversal of 77211661 is 16611277.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 59521225 + 17690436 = 7715^2 + 4206^2 .

It is a cyclic number.

It is not a de Polignac number, because 77211661 - 2²¹ = 75114509 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (77211691) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38605830 + 38605831.

It is an arithmetic number, because the mean of its divisors is an integer number (38605831).

Almost surely, 2^77211661 is an apocalyptic number.

It is an amenable number.

77211661 is a deficient number, since it is larger than the sum of its proper divisors (1).

77211661 is an equidigital number, since it uses as much as digits as its factorization.

77211661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3528, while the sum is 31.

The square root of 77211661 is about 8787.0166154389. The cubic root of 77211661 is about 425.8215453769.

The spelling of 77211661 in words is "seventy-seven million, two hundred eleven thousand, six hundred sixty-one".