3973397721 has 16 divisors (see below), whose sum is σ = 5336002560. Its totient is φ = 2629927440.

The previous prime is 3973397713. The next prime is 3973397749. The reversal of 3973397721 is 1277933793.

It is not a de Polignac number, because 3973397721 - 2³ = 3973397713 is a prime.

It is not an unprimeable number, because it can be changed into a prime (3973390721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 245716 + ... + 261386.

It is an arithmetic number, because the mean of its divisors is an integer number (333500160).

Almost surely, 2^3973397721 is an apocalyptic number.

It is an amenable number.

3973397721 is a deficient number, since it is larger than the sum of its proper divisors (1362604839).

3973397721 is a wasteful number, since it uses less digits than its factorization.

3973397721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16276.

The product of its digits is 1500282, while the sum is 51.

The square root of 3973397721 is about 63034.8928848142. The cubic root of 3973397721 is about 1583.8741813357.

The spelling of 3973397721 in words is "three billion, nine hundred seventy-three million, three hundred ninety-seven thousand, seven hundred twenty-one".