661277280 has 96 divisors (see below), whose sum is σ = 2087576064. Its totient is φ = 175955456.

The previous prime is 661277269. The next prime is 661277297. The reversal of 661277280 is 82772166.

It is a tau number, because it is divible by the number of its divisors (96).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 269017 + ... + 271463.

It is an arithmetic number, because the mean of its divisors is an integer number (21745584).

Almost surely, 2^661277280 is an apocalyptic number.

661277280 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 661277280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1043788032).

661277280 is an abundant number, since it is smaller than the sum of its proper divisors (1426298784).

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

661277280 is a wasteful number, since it uses less digits than its factorization.

661277280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3028 (or 3020 counting only the distinct ones).

The product of its (nonzero) digits is 56448, while the sum is 39.

The square root of 661277280 is about 25715.3121699893. The cubic root of 661277280 is about 871.2200612454.

The spelling of 661277280 in words is "six hundred sixty-one million, two hundred seventy-seven thousand, two hundred eighty".