66442407154561 has 4 divisors (see below), whose sum is σ = 66442432425300. Its totient is φ = 66442381883824.

The previous prime is 66442407154549. The next prime is 66442407154567. The reversal of 66442407154561 is 16545170424466.

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 38578197988225 + 27864209166336 = 6211135^2 + 5278656^2 .

It is a cyclic number.

It is not a de Polignac number, because 66442407154561 - 2⁹ = 66442407154049 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66442407154567) 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, 8164126 + ... + 14125783.

It is an arithmetic number, because the mean of its divisors is an integer number (16610608106325).

Almost surely, 2^{66442407154561} is an apocalyptic number.

It is an amenable number.

66442407154561 is a deficient number, since it is larger than the sum of its proper divisors (25270739).

66442407154561 is a wasteful number, since it uses less digits than its factorization.

66442407154561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25270738.

The product of its (nonzero) digits is 19353600, while the sum is 55.

The spelling of 66442407154561 in words is "sixty-six trillion, four hundred forty-two billion, four hundred seven million, one hundred fifty-four thousand, five hundred sixty-one".