1971661536 has 72 divisors (see below), whose sum is σ = 6038224920. Its totient is φ = 606663936.

The previous prime is 1971661519. The next prime is 1971661543. The reversal of 1971661536 is 6351661791.

1971661536 is a `hidden beast` number, since 19 + 7 + 16 + 615 + 3 + 6 = 666.

It is a tau number, because it is divible by the number of its divisors (72).

It is a junction number, because it is equal to n+sod(n) for n = 1971661491 and 1971661500.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 259566 + ... + 267053.

It is an arithmetic number, because the mean of its divisors is an integer number (83864235).

Almost surely, 2^1971661536 is an apocalyptic number.

1971661536 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

1971661536 is an abundant number, since it is smaller than the sum of its proper divisors (4066563384).

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

1971661536 is a wasteful number, since it uses less digits than its factorization.

1971661536 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 526648 (or 526637 counting only the distinct ones).

The product of its digits is 204120, while the sum is 45.

The square root of 1971661536 is about 44403.3955458364. The cubic root of 1971661536 is about 1253.9420163509.

The spelling of 1971661536 in words is "one billion, nine hundred seventy-one million, six hundred sixty-one thousand, five hundred thirty-six".