66361721 has 8 divisors (see below), whose sum is σ = 67253760. Its totient is φ = 65474928.

The previous prime is 66361709. The next prime is 66361723. The reversal of 66361721 is 12716366.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66361721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66361723) 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, 28520 + ... + 30758.

It is an arithmetic number, because the mean of its divisors is an integer number (8406720).

Almost surely, 2^66361721 is an apocalyptic number.

It is an amenable number.

66361721 is a deficient number, since it is larger than the sum of its proper divisors (892039).

66361721 is a wasteful number, since it uses less digits than its factorization.

66361721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2623.

The product of its digits is 9072, while the sum is 32.

The square root of 66361721 is about 8146.2703736127. The cubic root of 66361721 is about 404.8609409292.

The spelling of 66361721 in words is "sixty-six million, three hundred sixty-one thousand, seven hundred twenty-one".