661336615661440 has 64 divisors (see below), whose sum is σ = 1583898172785360. Its totient is φ = 264051036168192.

The previous prime is 661336615661347. The next prime is 661336615661443. The reversal of 661336615661440 is 44166516633166.

It is a tau number, because it is divible by the number of its divisors (64).

It is a super-2 number, since 2×661336615661440² (a number of 30 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661336615661443) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 944200617 + ... + 944900776.

Almost surely, 2^{661336615661440} is an apocalyptic number.

It is an amenable number.

661336615661440 is an abundant number, since it is smaller than the sum of its proper divisors (922561557123920).

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

661336615661440 is a wasteful number, since it uses less digits than its factorization.

661336615661440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1889101959 (or 1889101947 counting only the distinct ones).

The product of its (nonzero) digits is 33592320, while the sum is 58.

The spelling of 661336615661440 in words is "six hundred sixty-one trillion, three hundred thirty-six billion, six hundred fifteen million, six hundred sixty-one thousand, four hundred forty".