61721736918 has 64 divisors (see below), whose sum is σ = 127344960000. Its totient is φ = 19936122624.

The previous prime is 61721736883. The next prime is 61721736931. The reversal of 61721736918 is 81963712716.

It is a happy number.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 7115488 + ... + 7124156.

It is an arithmetic number, because the mean of its divisors is an integer number (1989765000).

Almost surely, 2^61721736918 is an apocalyptic number.

61721736918 is an abundant number, since it is smaller than the sum of its proper divisors (65623223082).

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

61721736918 is a wasteful number, since it uses less digits than its factorization.

61721736918 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9029.

The product of its digits is 762048, while the sum is 51.

The spelling of 61721736918 in words is "sixty-one billion, seven hundred twenty-one million, seven hundred thirty-six thousand, nine hundred eighteen".