66724639 has 2 divisors, whose sum is σ = 66724640. Its totient is φ = 66724638.

The previous prime is 66724601. The next prime is 66724649. The reversal of 66724639 is 93642766.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66724639 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 66724595 and 66724604.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66724649) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33362319 + 33362320.

It is an arithmetic number, because the mean of its divisors is an integer number (33362320).

Almost surely, 2^66724639 is an apocalyptic number.

66724639 is a deficient number, since it is larger than the sum of its proper divisors (1).

66724639 is an equidigital number, since it uses as much as digits as its factorization.

66724639 is an evil number, because the sum of its binary digits is even.

The product of its digits is 326592, while the sum is 43.

The square root of 66724639 is about 8168.5151037383. The cubic root of 66724639 is about 405.5976321335.

It can be divided in two parts, 6672 and 4639, that added together give a palindrome (11311).

The spelling of 66724639 in words is "sixty-six million, seven hundred twenty-four thousand, six hundred thirty-nine".