66216715 has 16 divisors (see below), whose sum is σ = 82519200. Its totient is φ = 50948352.

The previous prime is 66216697. The next prime is 66216727. The reversal of 66216715 is 51761266.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 66216715 - 2⁷ = 66216587 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 44656 + ... + 46114.

It is an arithmetic number, because the mean of its divisors is an integer number (5157450).

Almost surely, 2^66216715 is an apocalyptic number.

66216715 is a deficient number, since it is larger than the sum of its proper divisors (16302485).

66216715 is a wasteful number, since it uses less digits than its factorization.

66216715 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1806.

The product of its digits is 15120, while the sum is 34.

The square root of 66216715 is about 8137.3653598692. The cubic root of 66216715 is about 404.5658406976.

The spelling of 66216715 in words is "sixty-six million, two hundred sixteen thousand, seven hundred fifteen".