61081639481 has 2 divisors, whose sum is σ = 61081639482. Its totient is φ = 61081639480.

The previous prime is 61081639469. The next prime is 61081639517. The reversal of 61081639481 is 18493618016.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 43392639481 + 17689000000 = 208309^2 + 133000^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-61081639481 is a prime.

It is a super-2 number, since 2×61081639481² (a number of 22 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (61081639781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30540819740 + 30540819741.

It is an arithmetic number, because the mean of its divisors is an integer number (30540819741).

Almost surely, 2^61081639481 is an apocalyptic number.

It is an amenable number.

61081639481 is a deficient number, since it is larger than the sum of its proper divisors (1).

61081639481 is an equidigital number, since it uses as much as digits as its factorization.

61081639481 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 248832, while the sum is 47.

The spelling of 61081639481 in words is "sixty-one billion, eighty-one million, six hundred thirty-nine thousand, four hundred eighty-one".