1961981977 has 2 divisors, whose sum is σ = 1961981978. Its totient is φ = 1961981976.

The previous prime is 1961981963. The next prime is 1961981993. The reversal of 1961981977 is 7791891691.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1656571401 + 305410576 = 40701^2 + 17476^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1961981977 is a prime.

It is not a weakly prime, because it can be changed into another prime (1961981927) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 980990988 + 980990989.

It is an arithmetic number, because the mean of its divisors is an integer number (980990989).

Almost surely, 2^1961981977 is an apocalyptic number.

It is an amenable number.

1961981977 is a deficient number, since it is larger than the sum of its proper divisors (1).

1961981977 is an equidigital number, since it uses as much as digits as its factorization.

1961981977 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1714608, while the sum is 58.

The square root of 1961981977 is about 44294.2657349684. The cubic root of 1961981977 is about 1251.8866394673.

The spelling of 1961981977 in words is "one billion, nine hundred sixty-one million, nine hundred eighty-one thousand, nine hundred seventy-seven".