81510199990 has 32 divisors (see below), whose sum is σ = 152866704384. Its totient is φ = 31257441120.

The previous prime is 81510199987. The next prime is 81510199993. The reversal of 81510199990 is 9999101518.

It is an interprime number because it is at equal distance from previous prime (81510199987) and next prime (81510199993).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81510199993) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1195504 + ... + 1261843.

It is an arithmetic number, because the mean of its divisors is an integer number (4777084512).

Almost surely, 2^81510199990 is an apocalyptic number.

81510199990 is a deficient number, since it is larger than the sum of its proper divisors (71356504394).

81510199990 is a wasteful number, since it uses less digits than its factorization.

81510199990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2457492.

The product of its (nonzero) digits is 262440, while the sum is 52.

The spelling of 81510199990 in words is "eighty-one billion, five hundred ten million, one hundred ninety-nine thousand, nine hundred ninety".