3921987208 has 24 divisors (see below), whose sum is σ = 7439521950. Its totient is φ = 1938133824.

The previous prime is 3921987149. The next prime is 3921987221. The reversal of 3921987208 is 8027891293.

It can be written as a sum of positive squares in only one way, i.e., 3723684484 + 198302724 = 61022^2 + 14082^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1669891 + ... + 1672237.

Almost surely, 2^3921987208 is an apocalyptic number.

It is an amenable number.

3921987208 is a deficient number, since it is larger than the sum of its proper divisors (3517534742).

3921987208 is an frugal number, since it uses more digits than its factorization.

3921987208 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4789 (or 2438 counting only the distinct ones).

The product of its (nonzero) digits is 435456, while the sum is 49.

The square root of 3921987208 is about 62625.7711170090. The cubic root of 3921987208 is about 1577.0134267534.

The spelling of 3921987208 in words is "three billion, nine hundred twenty-one million, nine hundred eighty-seven thousand, two hundred eight".