3997921536 has 216 divisors, whose sum is σ = 13663109824. Its totient is φ = 1142138880.

The previous prime is 3997921489. The next prime is 3997921547. The reversal of 3997921536 is 6351297993.

It is a happy number.

3997921536 is a `hidden beast` number, since 39 + 9 + 79 + 2 + 1 + 536 = 666.

It is a tau number, because it is divible by the number of its divisors (216).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 430866 + ... + 440046.

Almost surely, 2^3997921536 is an apocalyptic number.

3997921536 is a gapful number since it is divisible by the number (36) 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 3997921536, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (6831554912).

3997921536 is an abundant number, since it is smaller than the sum of its proper divisors (9665188288).

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

3997921536 is an frugal number, since it uses more digits than its factorization.

3997921536 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9219 (or 9193 counting only the distinct ones).

The product of its digits is 2755620, while the sum is 54.

The square root of 3997921536 is about 63229.1193675825. The cubic root of 3997921536 is about 1587.1260580039.

The spelling of 3997921536 in words is "three billion, nine hundred ninety-seven million, nine hundred twenty-one thousand, five hundred thirty-six".