661516061 has 2 divisors, whose sum is σ = 661516062. Its totient is φ = 661516060.

The previous prime is 661516057. The next prime is 661516067. The reversal of 661516061 is 160615166.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 602702500 + 58813561 = 24550^2 + 7669^2 .

It is a cyclic number.

It is not a de Polignac number, because 661516061 - 2² = 661516057 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661516067) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330758030 + 330758031.

It is an arithmetic number, because the mean of its divisors is an integer number (330758031).

Almost surely, 2^661516061 is an apocalyptic number.

It is an amenable number.

661516061 is a deficient number, since it is larger than the sum of its proper divisors (1).

661516061 is an equidigital number, since it uses as much as digits as its factorization.

661516061 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6480, while the sum is 32.

The square root of 661516061 is about 25719.9545295088. The cubic root of 661516061 is about 871.3249117468.

The spelling of 661516061 in words is "six hundred sixty-one million, five hundred sixteen thousand, sixty-one".