661405260 has 24 divisors (see below), whose sum is σ = 1851934896. Its totient is φ = 176374720.

The previous prime is 661405253. The next prime is 661405271. The reversal of 661405260 is 62504166.

It is a Harshad number since it is a multiple of its sum of digits (30).

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, 5511651 + ... + 5511770.

It is an arithmetic number, because the mean of its divisors is an integer number (77163954).

Almost surely, 2^661405260 is an apocalyptic number.

661405260 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

661405260 is an abundant number, since it is smaller than the sum of its proper divisors (1190529636).

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

661405260 is a wasteful number, since it uses less digits than its factorization.

661405260 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11023433 (or 11023431 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 30.

The square root of 661405260 is about 25717.8004502718. The cubic root of 661405260 is about 871.2762613471.

It can be divided in two parts, 66 and 1405260, that added together give a triangular number (1405326 = T₁₆₇₆).

The spelling of 661405260 in words is "six hundred sixty-one million, four hundred five thousand, two hundred sixty".