1661115977 has 2 divisors, whose sum is σ = 1661115978. Its totient is φ = 1661115976.

The previous prime is 1661115947. The next prime is 1661115991. The reversal of 1661115977 is 7795111661.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1660073536 + 1042441 = 40744^2 + 1021^2 .

It is a cyclic number.

It is not a de Polignac number, because 1661115977 - 2⁸ = 1661115721 is a prime.

It is not a weakly prime, because it can be changed into another prime (1661115947) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 830557988 + 830557989.

It is an arithmetic number, because the mean of its divisors is an integer number (830557989).

Almost surely, 2^1661115977 is an apocalyptic number.

It is an amenable number.

1661115977 is a deficient number, since it is larger than the sum of its proper divisors (1).

1661115977 is an equidigital number, since it uses as much as digits as its factorization.

1661115977 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 79380, while the sum is 44.

The square root of 1661115977 is about 40756.7905630461. The cubic root of 1661115977 is about 1184.3134235473.

The spelling of 1661115977 in words is "one billion, six hundred sixty-one million, one hundred fifteen thousand, nine hundred seventy-seven".