661465771 has 2 divisors, whose sum is σ = 661465772. Its totient is φ = 661465770.

The previous prime is 661465621. The next prime is 661465781. The reversal of 661465771 is 177564166.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 661465771 - 2¹⁷ = 661334699 is a prime.

It is not a weakly prime, because it can be changed into another prime (661465781) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330732885 + 330732886.

It is an arithmetic number, because the mean of its divisors is an integer number (330732886).

Almost surely, 2^661465771 is an apocalyptic number.

661465771 is a deficient number, since it is larger than the sum of its proper divisors (1).

661465771 is an equidigital number, since it uses as much as digits as its factorization.

661465771 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 211680, while the sum is 43.

The square root of 661465771 is about 25718.9768653421. The cubic root of 661465771 is about 871.3028311338.

It can be divided in two parts, 66146 and 5771, that added together give a palindrome (71917).

The spelling of 661465771 in words is "six hundred sixty-one million, four hundred sixty-five thousand, seven hundred seventy-one".