661661011 has 16 divisors (see below), whose sum is σ = 729001728. Its totient is φ = 595548000.

The previous prime is 661661009. The next prime is 661661017. The reversal of 661661011 is 110166166.

It is a cyclic number.

It is not a de Polignac number, because 661661011 - 2¹ = 661661009 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661661017) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 775261 + ... + 776113.

It is an arithmetic number, because the mean of its divisors is an integer number (45562608).

Almost surely, 2^661661011 is an apocalyptic number.

661661011 is a deficient number, since it is larger than the sum of its proper divisors (67340717).

661661011 is a wasteful number, since it uses less digits than its factorization.

661661011 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1482.

The product of its (nonzero) digits is 1296, while the sum is 28.

The square root of 661661011 is about 25722.7722261812. The cubic root of 661661011 is about 871.3885480562.

The spelling of 661661011 in words is "six hundred sixty-one million, six hundred sixty-one thousand, eleven".