81021907707 has 32 divisors (see below), whose sum is σ = 125270530560. Its totient is φ = 46131325440.

The previous prime is 81021907691. The next prime is 81021907709. The reversal of 81021907707 is 70770912018.

It is not a de Polignac number, because 81021907707 - 2⁴ = 81021907691 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81021907709) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 996519 + ... + 1074752.

It is an arithmetic number, because the mean of its divisors is an integer number (3914704080).

Almost surely, 2^81021907707 is an apocalyptic number.

81021907707 is a deficient number, since it is larger than the sum of its proper divisors (44248622853).

81021907707 is a wasteful number, since it uses less digits than its factorization.

81021907707 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2071363.

The product of its (nonzero) digits is 49392, while the sum is 42.

The spelling of 81021907707 in words is "eighty-one billion, twenty-one million, nine hundred seven thousand, seven hundred seven".