66621081601 has 8 divisors (see below), whose sum is σ = 72446455080. Its totient is φ = 61007539968.

The previous prime is 66621081581. The next prime is 66621081613. The reversal of 66621081601 is 10618012666.

It can be written as a sum of positive squares in 4 ways, for example, as 14476902400 + 52144179201 = 120320^2 + 228351^2 .

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-66621081601 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (37).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66621084601) 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, 52957306 + ... + 52958563.

It is an arithmetic number, because the mean of its divisors is an integer number (9055806885).

Almost surely, 2^66621081601 is an apocalyptic number.

It is an amenable number.

66621081601 is a deficient number, since it is larger than the sum of its proper divisors (5825373479).

66621081601 is a wasteful number, since it uses less digits than its factorization.

66621081601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 105915923.

The product of its (nonzero) digits is 20736, while the sum is 37.

The spelling of 66621081601 in words is "sixty-six billion, six hundred twenty-one million, eighty-one thousand, six hundred one".