661010661 has 12 divisors (see below), whose sum is σ = 980598892. Its totient is φ = 428763456.

The previous prime is 661010653. The next prime is 661010681. The reversal of 661010661 is 166010166.

It can be written as a sum of positive squares in 2 ways, for example, as 590198436 + 70812225 = 24294^2 + 8415^2 .

It is not a de Polignac number, because 661010661 - 2³ = 661010653 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661010681) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 992176 + ... + 992841.

Almost surely, 2^661010661 is an apocalyptic number.

It is an amenable number.

661010661 is a deficient number, since it is larger than the sum of its proper divisors (319588231).

661010661 is a wasteful number, since it uses less digits than its factorization.

661010661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1985060 (or 1985057 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 27.

The square root of 661010661 is about 25710.1275959494. The cubic root of 661010661 is about 871.1029570424.

It can be divided in two parts, 6610 and 10661, that added together give a palindrome (17271).

The spelling of 661010661 in words is "six hundred sixty-one million, ten thousand, six hundred sixty-one".