161020661 has 2 divisors, whose sum is σ = 161020662. Its totient is φ = 161020660.

The previous prime is 161020627. The next prime is 161020667. The reversal of 161020661 is 166020161.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 127554436 + 33466225 = 11294^2 + 5785^2 .

It is an emirp because it is prime and its reverse (166020161) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 161020661 - 2¹⁰ = 161019637 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (161020667) 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 as a sum of consecutive naturals, namely, 80510330 + 80510331.

It is an arithmetic number, because the mean of its divisors is an integer number (80510331).

Almost surely, 2^161020661 is an apocalyptic number.

It is an amenable number.

161020661 is a deficient number, since it is larger than the sum of its proper divisors (1).

161020661 is an equidigital number, since it uses as much as digits as its factorization.

161020661 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 432, while the sum is 23.

The square root of 161020661 is about 12689.3916717863. The cubic root of 161020661 is about 544.0354524275.

The spelling of 161020661 in words is "one hundred sixty-one million, twenty thousand, six hundred sixty-one".