207121061561 has 4 divisors (see below), whose sum is σ = 207218349300. Its totient is φ = 207023773824.

The previous prime is 207121061551. The next prime is 207121061593. The reversal of 207121061561 is 165160121702.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 165160121702 = 2 ⋅82580060851.

It can be written as a sum of positive squares in 2 ways, for example, as 34547285161 + 172573776400 = 185869^2 + 415420^2 .

It is a cyclic number.

It is not a de Polignac number, because 207121061561 - 2²² = 207116867257 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (207121061551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 48640676 + ... + 48644933.

It is an arithmetic number, because the mean of its divisors is an integer number (51804587325).

Almost surely, 2^207121061561 is an apocalyptic number.

It is an amenable number.

207121061561 is a deficient number, since it is larger than the sum of its proper divisors (97287739).

207121061561 is an equidigital number, since it uses as much as digits as its factorization.

207121061561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 97287738.

The product of its (nonzero) digits is 5040, while the sum is 32.

The spelling of 207121061561 in words is "two hundred seven billion, one hundred twenty-one million, sixty-one thousand, five hundred sixty-one".