61641215981 has 2 divisors, whose sum is σ = 61641215982. Its totient is φ = 61641215980.

The previous prime is 61641215939. The next prime is 61641216023. The reversal of 61641215981 is 18951214616.

It is a balanced prime because it is at equal distance from previous prime (61641215939) and next prime (61641216023).

It can be written as a sum of positive squares in only one way, i.e., 46544179081 + 15097036900 = 215741^2 + 122870^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-61641215981 is a prime.

It is a super-2 number, since 2×61641215981² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61641211981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30820607990 + 30820607991.

It is an arithmetic number, because the mean of its divisors is an integer number (30820607991).

Almost surely, 2^61641215981 is an apocalyptic number.

It is an amenable number.

61641215981 is a deficient number, since it is larger than the sum of its proper divisors (1).

61641215981 is an equidigital number, since it uses as much as digits as its factorization.

61641215981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 103680, while the sum is 44.

The spelling of 61641215981 in words is "sixty-one billion, six hundred forty-one million, two hundred fifteen thousand, nine hundred eighty-one".