81151844639 has 2 divisors, whose sum is σ = 81151844640. Its totient is φ = 81151844638.

The previous prime is 81151844573. The next prime is 81151844677. The reversal of 81151844639 is 93644815118.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81151844639 - 2¹⁶ = 81151779103 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81151844239) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40575922319 + 40575922320.

It is an arithmetic number, because the mean of its divisors is an integer number (40575922320).

Almost surely, 2^81151844639 is an apocalyptic number.

81151844639 is a deficient number, since it is larger than the sum of its proper divisors (1).

81151844639 is an equidigital number, since it uses as much as digits as its factorization.

81151844639 is an evil number, because the sum of its binary digits is even.

The product of its digits is 829440, while the sum is 50.

The spelling of 81151844639 in words is "eighty-one billion, one hundred fifty-one million, eight hundred forty-four thousand, six hundred thirty-nine".