661152780 has 120 divisors (see below), whose sum is σ = 2196155808. Its totient is φ = 165929472.

The previous prime is 661152749. The next prime is 661152799. The reversal of 661152780 is 87251166.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 15537 + ... + 39543.

Almost surely, 2^661152780 is an apocalyptic number.

661152780 is a gapful number since it is divisible by the number (60) 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 661152780, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1098077904).

661152780 is an abundant number, since it is smaller than the sum of its proper divisors (1535003028).

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

661152780 is a wasteful number, since it uses less digits than its factorization.

661152780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24045 (or 24034 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 36.

The square root of 661152780 is about 25712.8913193363. The cubic root of 661152780 is about 871.1653823642.

The spelling of 661152780 in words is "six hundred sixty-one million, one hundred fifty-two thousand, seven hundred eighty".