3972721 has 8 divisors (see below), whose sum is σ = 4224960. Its totient is φ = 3727152.

The previous prime is 3972697. The next prime is 3972737. The reversal of 3972721 is 1272793.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 3972721 - 2⁷ = 3972593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (3972751) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 411 + ... + 2848.

It is an arithmetic number, because the mean of its divisors is an integer number (528120).

Almost surely, 2^3972721 is an apocalyptic number.

It is an amenable number.

3972721 is a deficient number, since it is larger than the sum of its proper divisors (252239).

3972721 is a wasteful number, since it uses less digits than its factorization.

3972721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3335.

The product of its digits is 5292, while the sum is 31.

The square root of 3972721 is about 1993.1685829352. The cubic root of 3972721 is about 158.3784258147.

The spelling of 3972721 in words is "three million, nine hundred seventy-two thousand, seven hundred twenty-one".