81220742387 has 2 divisors, whose sum is σ = 81220742388. Its totient is φ = 81220742386.

The previous prime is 81220742381. The next prime is 81220742459. The reversal of 81220742387 is 78324702218.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81220742387 - 2⁴ = 81220742371 is a prime.

It is not a weakly prime, because it can be changed into another prime (81220742381) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40610371193 + 40610371194.

It is an arithmetic number, because the mean of its divisors is an integer number (40610371194).

Almost surely, 2^81220742387 is an apocalyptic number.

81220742387 is a deficient number, since it is larger than the sum of its proper divisors (1).

81220742387 is an equidigital number, since it uses as much as digits as its factorization.

81220742387 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 301056, while the sum is 44.

The spelling of 81220742387 in words is "eighty-one billion, two hundred twenty million, seven hundred forty-two thousand, three hundred eighty-seven".