39916721 has 8 divisors (see below), whose sum is σ = 43065960. Its totient is φ = 36778752.

The previous prime is 39916717. The next prime is 39916727. The reversal of 39916721 is 12761993.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 1290496 + 38626225 = 1136^2 + 6215^2 .

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 39916721 - 2² = 39916717 is a prime.

It is a Duffinian number.

It is a zygodrome in base 12.

It is not an unprimeable number, because it can be changed into a prime (39916727) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5465 + ... + 10473.

It is an arithmetic number, because the mean of its divisors is an integer number (5383245).

Almost surely, 2^39916721 is an apocalyptic number.

It is an amenable number.

39916721 is a deficient number, since it is larger than the sum of its proper divisors (3149239).

39916721 is a wasteful number, since it uses less digits than its factorization.

39916721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5635.

The product of its digits is 20412, while the sum is 38.

The square root of 39916721 is about 6317.9681069154. The cubic root of 39916721 is about 341.7576826199.

The spelling of 39916721 in words is "thirty-nine million, nine hundred sixteen thousand, seven hundred twenty-one".