661807380 has 72 divisors (see below), whose sum is σ = 2006599392. Its totient is φ = 162903936.

The previous prime is 661807379. The next prime is 661807387. The reversal of 661807380 is 83708166.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661807387) by changing a digit.

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 23 ways as a sum of consecutive naturals, for example, 22494 + ... + 42773.

It is an arithmetic number, because the mean of its divisors is an integer number (27869436).

Almost surely, 2^661807380 is an apocalyptic number.

661807380 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

661807380 is an abundant number, since it is smaller than the sum of its proper divisors (1344792012).

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

661807380 is a wasteful number, since it uses less digits than its factorization.

661807380 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65305 (or 65290 counting only the distinct ones).

The product of its (nonzero) digits is 48384, while the sum is 39.

The square root of 661807380 is about 25725.6171937623. The cubic root of 661807380 is about 871.4527979085.

The spelling of 661807380 in words is "six hundred sixty-one million, eight hundred seven thousand, three hundred eighty".