661987937688 has 192 divisors, whose sum is σ = 2119456627200. Its totient is φ = 170367079680.

The previous prime is 661987937591. The next prime is 661987937713. The reversal of 661987937688 is 886739789166.

It is a super-2 number, since 2×661987937688² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1175281 + ... + 1644767.

It is an arithmetic number, because the mean of its divisors is an integer number (11038836600).

Almost surely, 2^661987937688 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 661987937688, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1059728313600).

661987937688 is an abundant number, since it is smaller than the sum of its proper divisors (1457468689512).

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

661987937688 is a wasteful number, since it uses less digits than its factorization.

661987937688 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 469630 (or 469619 counting only the distinct ones).

The product of its digits is 1316818944, while the sum is 78.

The spelling of 661987937688 in words is "six hundred sixty-one billion, nine hundred eighty-seven million, nine hundred thirty-seven thousand, six hundred eighty-eight".