661501133100251 has 4 divisors (see below), whose sum is σ = 661577369265792. Its totient is φ = 661424896934712.

The previous prime is 661501133100217. The next prime is 661501133100253. The reversal of 661501133100251 is 152001331105166.

661501133100251 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is a cyclic number.

It is not a de Polignac number, because 661501133100251 - 2³⁴ = 661483953231067 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661501133100253) 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, 38118069755 + ... + 38118087108.

It is an arithmetic number, because the mean of its divisors is an integer number (165394342316448).

Almost surely, 2^{661501133100251} is an apocalyptic number.

661501133100251 is a deficient number, since it is larger than the sum of its proper divisors (76236165541).

661501133100251 is an equidigital number, since it uses as much as digits as its factorization.

661501133100251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 76236165540.

The product of its (nonzero) digits is 16200, while the sum is 35.

The spelling of 661501133100251 in words is "six hundred sixty-one trillion, five hundred one billion, one hundred thirty-three million, one hundred thousand, two hundred fifty-one".