39540721 has 8 divisors (see below), whose sum is σ = 43229088. Its totient is φ = 35868000.

The previous prime is 39540719. The next prime is 39540727. The reversal of 39540721 is 12704593.

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 39540721 - 2¹ = 39540719 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (39540727) 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, 1741 + ... + 9061.

It is an arithmetic number, because the mean of its divisors is an integer number (5403636).

Almost surely, 2^39540721 is an apocalyptic number.

It is an amenable number.

39540721 is a deficient number, since it is larger than the sum of its proper divisors (3688367).

39540721 is a wasteful number, since it uses less digits than its factorization.

39540721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7823.

The product of its (nonzero) digits is 7560, while the sum is 31.

The square root of 39540721 is about 6288.1412993030. The cubic root of 39540721 is about 340.6812207064.

The spelling of 39540721 in words is "thirty-nine million, five hundred forty thousand, seven hundred twenty-one".