661799370 has 64 divisors (see below), whose sum is σ = 1620074880. Its totient is φ = 172972800.

The previous prime is 661799357. The next prime is 661799381. The reversal of 661799370 is 73997166.

It is a super-2 number, since 2×661799370² = 875956812264793800, which contains 22 as substring.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 770001 + ... + 770859.

It is an arithmetic number, because the mean of its divisors is an integer number (25313670).

Almost surely, 2^661799370 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661799370, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (810037440).

661799370 is an abundant number, since it is smaller than the sum of its proper divisors (958275510).

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

661799370 is a wasteful number, since it uses less digits than its factorization.

661799370 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1351.

The product of its (nonzero) digits is 428652, while the sum is 48.

The square root of 661799370 is about 25725.4615118952. The cubic root of 661799370 is about 871.4492820995.

The spelling of 661799370 in words is "six hundred sixty-one million, seven hundred ninety-nine thousand, three hundred seventy".