66415718261 has 4 divisors (see below), whose sum is σ = 69911282400. Its totient is φ = 62920154124.

The previous prime is 66415718219. The next prime is 66415718263. The reversal of 66415718261 is 16281751466.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66415718261 is a prime.

It is a super-2 number, since 2×66415718261² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66415718263) 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, 1747782041 + ... + 1747782078.

It is an arithmetic number, because the mean of its divisors is an integer number (17477820600).

Almost surely, 2^66415718261 is an apocalyptic number.

It is an amenable number.

66415718261 is a deficient number, since it is larger than the sum of its proper divisors (3495564139).

66415718261 is a wasteful number, since it uses less digits than its factorization.

66415718261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3495564138.

The product of its digits is 483840, while the sum is 47.

The spelling of 66415718261 in words is "sixty-six billion, four hundred fifteen million, seven hundred eighteen thousand, two hundred sixty-one".