81611621206 has 4 divisors (see below), whose sum is σ = 122417431812. Its totient is φ = 40805810602.

The previous prime is 81611621131. The next prime is 81611621219. The reversal of 81611621206 is 60212611618.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20402905300 + ... + 20402905303.

It is an arithmetic number, because the mean of its divisors is an integer number (30604357953).

Almost surely, 2^81611621206 is an apocalyptic number.

81611621206 is a deficient number, since it is larger than the sum of its proper divisors (40805810606).

81611621206 is a wasteful number, since it uses less digits than its factorization.

81611621206 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40805810605.

The product of its (nonzero) digits is 6912, while the sum is 34.

The spelling of 81611621206 in words is "eighty-one billion, six hundred eleven million, six hundred twenty-one thousand, two hundred six".