61681979840 has 56 divisors (see below), whose sum is σ = 158178703200. Its totient is φ = 22774883328.

The previous prime is 61681979837. The next prime is 61681979857. The reversal of 61681979840 is 4897918616.

It is a self number, because there is not a number n which added to its sum of digits gives 61681979840.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7409540 + ... + 7417859.

It is an arithmetic number, because the mean of its divisors is an integer number (2824619700).

Almost surely, 2^61681979840 is an apocalyptic number.

It is an amenable number.

61681979840 is an abundant number, since it is smaller than the sum of its proper divisors (96496723360).

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

61681979840 is a wasteful number, since it uses less digits than its factorization.

61681979840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14827429 (or 14827419 counting only the distinct ones).

The product of its (nonzero) digits is 5225472, while the sum is 59.

The spelling of 61681979840 in words is "sixty-one billion, six hundred eighty-one million, nine hundred seventy-nine thousand, eight hundred forty".