1661385277 has 2 divisors, whose sum is σ = 1661385278. Its totient is φ = 1661385276.

The previous prime is 1661385241. The next prime is 1661385287. The reversal of 1661385277 is 7725831661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1170939961 + 490445316 = 34219^2 + 22146^2 .

It is a cyclic number.

It is not a de Polignac number, because 1661385277 - 2¹⁵ = 1661352509 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1661385287) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 830692638 + 830692639.

It is an arithmetic number, because the mean of its divisors is an integer number (830692639).

Almost surely, 2^1661385277 is an apocalyptic number.

It is an amenable number.

1661385277 is a deficient number, since it is larger than the sum of its proper divisors (1).

1661385277 is an equidigital number, since it uses as much as digits as its factorization.

1661385277 is an evil number, because the sum of its binary digits is even.

The product of its digits is 423360, while the sum is 46.

The square root of 1661385277 is about 40760.0941731002. The cubic root of 1661385277 is about 1184.3774203574.

The spelling of 1661385277 in words is "one billion, six hundred sixty-one million, three hundred eighty-five thousand, two hundred seventy-seven".