3947218538 has 4 divisors (see below), whose sum is σ = 5920827810. Its totient is φ = 1973609268.

The previous prime is 3947218537. The next prime is 3947218553. The reversal of 3947218538 is 8358127493.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 2655031729 + 1292186809 = 51527^2 + 35947^2 .

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (3947218537) by changing a digit.

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, 986804633 + ... + 986804636.

Almost surely, 2^3947218538 is an apocalyptic number.

3947218538 is a deficient number, since it is larger than the sum of its proper divisors (1973609272).

3947218538 is a wasteful number, since it uses less digits than its factorization.

3947218538 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1973609271.

The product of its digits is 1451520, while the sum is 50.

The square root of 3947218538 is about 62826.8934294861. The cubic root of 3947218538 is about 1580.3880019703.

The spelling of 3947218538 in words is "three billion, nine hundred forty-seven million, two hundred eighteen thousand, five hundred thirty-eight".