661994981476 has 6 divisors (see below), whose sum is σ = 1158491217590. Its totient is φ = 330997490736.

The previous prime is 661994981449. The next prime is 661994981519. The reversal of 661994981476 is 674189499166.

It can be written as a sum of positive squares in only one way, i.e., 650242253376 + 11752728100 = 806376^2 + 108410^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82749372681 + ... + 82749372688.

Almost surely, 2^661994981476 is an apocalyptic number.

It is an amenable number.

661994981476 is a deficient number, since it is larger than the sum of its proper divisors (496496236114).

661994981476 is a wasteful number, since it uses less digits than its factorization.

661994981476 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 165498745373 (or 165498745371 counting only the distinct ones).

The product of its digits is 141087744, while the sum is 70.

The spelling of 661994981476 in words is "six hundred sixty-one billion, nine hundred ninety-four million, nine hundred eighty-one thousand, four hundred seventy-six".