2661761021 has 2 divisors, whose sum is σ = 2661761022. Its totient is φ = 2661761020.

The previous prime is 2661760999. The next prime is 2661761033. The reversal of 2661761021 is 1201671662.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2168299225 + 493461796 = 46565^2 + 22214^2 .

It is a cyclic number.

It is not a de Polignac number, because 2661761021 - 2²⁶ = 2594652157 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2661761321) 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 as a sum of consecutive naturals, namely, 1330880510 + 1330880511.

It is an arithmetic number, because the mean of its divisors is an integer number (1330880511).

Almost surely, 2^2661761021 is an apocalyptic number.

It is an amenable number.

2661761021 is a deficient number, since it is larger than the sum of its proper divisors (1).

2661761021 is an equidigital number, since it uses as much as digits as its factorization.

2661761021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6048, while the sum is 32.

The square root of 2661761021 is about 51592.2573745325. The cubic root of 2661761021 is about 1385.8716805478.

The spelling of 2661761021 in words is "two billion, six hundred sixty-one million, seven hundred sixty-one thousand, twenty-one".