39706721 has 2 divisors, whose sum is σ = 39706722. Its totient is φ = 39706720.

The previous prime is 39706651. The next prime is 39706741. The reversal of 39706721 is 12760793.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 38887696 + 819025 = 6236^2 + 905^2 .

It is a cyclic number.

It is not a de Polignac number, because 39706721 - 2¹⁸ = 39444577 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (39706741) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 19853360 + 19853361.

It is an arithmetic number, because the mean of its divisors is an integer number (19853361).

Almost surely, 2^39706721 is an apocalyptic number.

It is an amenable number.

39706721 is a deficient number, since it is larger than the sum of its proper divisors (1).

39706721 is an equidigital number, since it uses as much as digits as its factorization.

39706721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 15876, while the sum is 35.

The square root of 39706721 is about 6301.3269237519. The cubic root of 39706721 is about 341.1573048110.

The spelling of 39706721 in words is "thirty-nine million, seven hundred six thousand, seven hundred twenty-one".