61081639639 has 2 divisors, whose sum is σ = 61081639640. Its totient is φ = 61081639638.

The previous prime is 61081639613. The next prime is 61081639657. The reversal of 61081639639 is 93693618016.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 61081639639 - 2²¹ = 61079542487 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61081630639) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30540819819 + 30540819820.

It is an arithmetic number, because the mean of its divisors is an integer number (30540819820).

Almost surely, 2^61081639639 is an apocalyptic number.

61081639639 is a deficient number, since it is larger than the sum of its proper divisors (1).

61081639639 is an equidigital number, since it uses as much as digits as its factorization.

61081639639 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1259712, while the sum is 52.

The spelling of 61081639639 in words is "sixty-one billion, eighty-one million, six hundred thirty-nine thousand, six hundred thirty-nine".