3951866638 has 4 divisors (see below), whose sum is σ = 5927799960. Its totient is φ = 1975933318.

The previous prime is 3951866617. The next prime is 3951866657. The reversal of 3951866638 is 8366681593.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 8366681593 = 2437 ⋅3433189.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 987966658 + ... + 987966661.

It is an arithmetic number, because the mean of its divisors is an integer number (1481949990).

Almost surely, 2^3951866638 is an apocalyptic number.

3951866638 is a deficient number, since it is larger than the sum of its proper divisors (1975933322).

3951866638 is a wasteful number, since it uses less digits than its factorization.

3951866638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1975933321.

The product of its digits is 5598720, while the sum is 55.

The square root of 3951866638 is about 62863.8738704512. The cubic root of 3951866638 is about 1581.0080943133.

The spelling of 3951866638 in words is "three billion, nine hundred fifty-one million, eight hundred sixty-six thousand, six hundred thirty-eight".