661615021189 has 2 divisors, whose sum is σ = 661615021190. Its totient is φ = 661615021188.

The previous prime is 661615021159. The next prime is 661615021213. The reversal of 661615021189 is 981120516166.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 522945922500 + 138669098689 = 723150^2 + 372383^2 .

It is a cyclic number.

It is not a de Polignac number, because 661615021189 - 2⁵ = 661615021157 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661615021159) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330807510594 + 330807510595.

It is an arithmetic number, because the mean of its divisors is an integer number (330807510595).

Almost surely, 2^661615021189 is an apocalyptic number.

It is an amenable number.

661615021189 is a deficient number, since it is larger than the sum of its proper divisors (1).

661615021189 is an equidigital number, since it uses as much as digits as its factorization.

661615021189 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 155520, while the sum is 46.

The spelling of 661615021189 in words is "six hundred sixty-one billion, six hundred fifteen million, twenty-one thousand, one hundred eighty-nine".