661131264 has 104 divisors (see below), whose sum is σ = 1778692032. Its totient is φ = 218398720.

The previous prime is 661131257. The next prime is 661131283. The reversal of 661131264 is 462131166.

It is a nude number because it is divisible by every one of its digits.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2125669 + ... + 2125979.

It is an arithmetic number, because the mean of its divisors is an integer number (17102808).

Almost surely, 2^661131264 is an apocalyptic number.

661131264 is a gapful number since it is divisible by the number (64) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661131264, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (889346016).

661131264 is an abundant number, since it is smaller than the sum of its proper divisors (1117560768).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

661131264 is a wasteful number, since it uses less digits than its factorization.

661131264 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 511 (or 489 counting only the distinct ones).

The product of its digits is 5184, while the sum is 30.

The square root of 661131264 is about 25712.4729265779. The cubic root of 661131264 is about 871.1559321038.

The spelling of 661131264 in words is "six hundred sixty-one million, one hundred thirty-one thousand, two hundred sixty-four".