661013161 has 2 divisors, whose sum is σ = 661013162. Its totient is φ = 661013160.

The previous prime is 661013149. The next prime is 661013183. The reversal of 661013161 is 161310166.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 537358761 + 123654400 = 23181^2 + 11120^2 .

It is a cyclic number.

It is not a de Polignac number, because 661013161 - 2²⁷ = 526795433 is a prime.

It is not a weakly prime, because it can be changed into another prime (661013131) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330506580 + 330506581.

It is an arithmetic number, because the mean of its divisors is an integer number (330506581).

Almost surely, 2^661013161 is an apocalyptic number.

It is an amenable number.

661013161 is a deficient number, since it is larger than the sum of its proper divisors (1).

661013161 is an equidigital number, since it uses as much as digits as its factorization.

661013161 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 648, while the sum is 25.

The square root of 661013161 is about 25710.1762148765. The cubic root of 661013161 is about 871.1040552368.

The spelling of 661013161 in words is "six hundred sixty-one million, thirteen thousand, one hundred sixty-one".