1971931640 has 128 divisors (see below), whose sum is σ = 5170176000. Its totient is φ = 662957568.

The previous prime is 1971931639. The next prime is 1971931651. The reversal of 1971931640 is 461391791.

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, 5286494 + ... + 5286866.

It is an arithmetic number, because the mean of its divisors is an integer number (40392000).

Almost surely, 2^1971931640 is an apocalyptic number.

1971931640 is a gapful number since it is divisible by the number (10) 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 1971931640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2585088000).

1971931640 is an abundant number, since it is smaller than the sum of its proper divisors (3198244360).

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

1971931640 is a wasteful number, since it uses less digits than its factorization.

1971931640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 709 (or 705 counting only the distinct ones).

The product of its (nonzero) digits is 40824, while the sum is 41.

The square root of 1971931640 is about 44406.4369207889. The cubic root of 1971931640 is about 1253.9992741988. Note that the first 3 decimals are identical.

The spelling of 1971931640 in words is "one billion, nine hundred seventy-one million, nine hundred thirty-one thousand, six hundred forty".