1971857664 has 108 divisors (see below), whose sum is σ = 6497598016. Its totient is φ = 563383296.

The previous prime is 1971857651. The next prime is 1971857669. The reversal of 1971857664 is 4667581791.

1971857664 is a `hidden beast` number, since 1 + 9 + 7 + 1 + 8 + 576 + 64 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 1971857664.

It is not an unprimeable number, because it can be changed into a prime (1971857669) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 45004 + ... + 77259.

Almost surely, 2^1971857664 is an apocalyptic number.

1971857664 is a gapful number since it is divisible by the number (14) formed by its first and last digit.

It is an amenable number.

1971857664 is an abundant number, since it is smaller than the sum of its proper divisors (4525740352).

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

1971857664 is a wasteful number, since it uses less digits than its factorization.

1971857664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 122292 (or 122275 counting only the distinct ones).

The product of its digits is 2540160, while the sum is 54.

The square root of 1971857664 is about 44405.6039706702. The cubic root of 1971857664 is about 1253.9835929570.

The spelling of 1971857664 in words is "one billion, nine hundred seventy-one million, eight hundred fifty-seven thousand, six hundred sixty-four".