31721723880 has 320 divisors, whose sum is σ = 121124203200. Its totient is φ = 6590868480.

The previous prime is 31721723867. The next prime is 31721723881. The reversal of 31721723880 is 8832712713.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is not an unprimeable number, because it can be changed into a prime (31721723881) by changing a digit.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 3164316 + ... + 3174324.

It is an arithmetic number, because the mean of its divisors is an integer number (378513135).

Almost surely, 2^31721723880 is an apocalyptic number.

31721723880 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 31721723880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (60562101600).

31721723880 is an abundant number, since it is smaller than the sum of its proper divisors (89402479320).

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

31721723880 is a wasteful number, since it uses less digits than its factorization.

31721723880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10062 (or 10037 counting only the distinct ones).

The product of its (nonzero) digits is 112896, while the sum is 42.

The spelling of 31721723880 in words is "thirty-one billion, seven hundred twenty-one million, seven hundred twenty-three thousand, eight hundred eighty".