66215797 has 4 divisors (see below), whose sum is σ = 66314860. Its totient is φ = 66116736.

The previous prime is 66215777. The next prime is 66215801. The reversal of 66215797 is 79751266.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 8059921 + 58155876 = 2839^2 + 7626^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66215797 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66215777) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 48522 + ... + 49867.

It is an arithmetic number, because the mean of its divisors is an integer number (16578715).

Almost surely, 2^66215797 is an apocalyptic number.

It is an amenable number.

66215797 is a deficient number, since it is larger than the sum of its proper divisors (99063).

66215797 is an equidigital number, since it uses as much as digits as its factorization.

66215797 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 99062.

The product of its digits is 158760, while the sum is 43.

The square root of 66215797 is about 8137.3089532105. The cubic root of 66215797 is about 404.5639711135.

The spelling of 66215797 in words is "sixty-six million, two hundred fifteen thousand, seven hundred ninety-seven".