81228989923 has 2 divisors, whose sum is σ = 81228989924. Its totient is φ = 81228989922.

The previous prime is 81228989873. The next prime is 81228989983. The reversal of 81228989923 is 32998982218.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81228989923 - 2¹³ = 81228981731 is a prime.

It is not a weakly prime, because it can be changed into another prime (81228989983) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40614494961 + 40614494962.

It is an arithmetic number, because the mean of its divisors is an integer number (40614494962).

Almost surely, 2^81228989923 is an apocalyptic number.

81228989923 is a deficient number, since it is larger than the sum of its proper divisors (1).

81228989923 is an equidigital number, since it uses as much as digits as its factorization.

81228989923 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8957952, while the sum is 61.

The spelling of 81228989923 in words is "eighty-one billion, two hundred twenty-eight million, nine hundred eighty-nine thousand, nine hundred twenty-three".