661072332121 has 4 divisors (see below), whose sum is σ = 661296199732. Its totient is φ = 660848464512.

The previous prime is 661072332113. The next prime is 661072332161. The reversal of 661072332121 is 121233270166.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 121233270166 = 2 ⋅60616635083.

It can be written as a sum of positive squares in 2 ways, for example, as 258531571600 + 402540760521 = 508460^2 + 634461^2 .

It is a cyclic number.

It is not a de Polignac number, because 661072332121 - 2³ = 661072332113 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661072332161) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 111929376 + ... + 111935281.

It is an arithmetic number, because the mean of its divisors is an integer number (165324049933).

Almost surely, 2^661072332121 is an apocalyptic number.

It is an amenable number.

661072332121 is a deficient number, since it is larger than the sum of its proper divisors (223867611).

661072332121 is a wasteful number, since it uses less digits than its factorization.

661072332121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 223867610.

The product of its (nonzero) digits is 18144, while the sum is 34.

The spelling of 661072332121 in words is "six hundred sixty-one billion, seventy-two million, three hundred thirty-two thousand, one hundred twenty-one".