66541721038551 has 72 divisors (see below), whose sum is σ = 109567242696912. Its totient is φ = 40325964307200.

The previous prime is 66541721038537. The next prime is 66541721038577. The reversal of 66541721038551 is 15583012714566.

66541721038551 is a `hidden beast` number, since 6 + 6 + 5 + 4 + 1 + 72 + 10 + 3 + 8 + 551 = 666.

It is not a de Polignac number, because 66541721038551 - 2⁶ = 66541721038487 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66541721037551) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 595678335 + ... + 595790031.

Almost surely, 2^{66541721038551} is an apocalyptic number.

66541721038551 is a deficient number, since it is larger than the sum of its proper divisors (43025521658361).

66541721038551 is a wasteful number, since it uses less digits than its factorization.

66541721038551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 131995 (or 131972 counting only the distinct ones).

The product of its (nonzero) digits is 6048000, while the sum is 54.

The spelling of 66541721038551 in words is "sixty-six trillion, five hundred forty-one billion, seven hundred twenty-one million, thirty-eight thousand, five hundred fifty-one".