1661928761 has 2 divisors, whose sum is σ = 1661928762. Its totient is φ = 1661928760.

The previous prime is 1661928757. The next prime is 1661928797. The reversal of 1661928761 is 1678291661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 907877161 + 754051600 = 30131^2 + 27460^2 .

It is a cyclic number.

It is not a de Polignac number, because 1661928761 - 2² = 1661928757 is a prime.

It is not a weakly prime, because it can be changed into another prime (1661925761) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 830964380 + 830964381.

It is an arithmetic number, because the mean of its divisors is an integer number (830964381).

Almost surely, 2^1661928761 is an apocalyptic number.

It is an amenable number.

1661928761 is a deficient number, since it is larger than the sum of its proper divisors (1).

1661928761 is an equidigital number, since it uses as much as digits as its factorization.

1661928761 is an evil number, because the sum of its binary digits is even.

The product of its digits is 217728, while the sum is 47.

The square root of 1661928761 is about 40766.7604918517. The cubic root of 1661928761 is about 1184.5065535593.

The spelling of 1661928761 in words is "one billion, six hundred sixty-one million, nine hundred twenty-eight thousand, seven hundred sixty-one".