661312512 has 440 divisors, whose sum is σ = 2425351104. Its totient is φ = 175177728.

The previous prime is 661312501. The next prime is 661312571. The reversal of 661312512 is 215213166.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

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, 9870303 + ... + 9870369.

Almost surely, 2^661312512 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661312512, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1212675552).

661312512 is an abundant number, since it is smaller than the sum of its proper divisors (1764038592).

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

661312512 is a wasteful number, since it uses less digits than its factorization.

661312512 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 123 (or 96 counting only the distinct ones).

The product of its digits is 2160, while the sum is 27.

The square root of 661312512 is about 25715.9972001865. The cubic root of 661312512 is about 871.2355334641.

Adding to 661312512 its reverse (215213166), we get a palindrome (876525678).

The spelling of 661312512 in words is "six hundred sixty-one million, three hundred twelve thousand, five hundred twelve".