81491206 has 8 divisors (see below), whose sum is σ = 122397264. Its totient is φ = 40692120.

The previous prime is 81491203. The next prime is 81491237. The reversal of 81491206 is 60219418.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81491203) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 24810 + ... + 27901.

It is an arithmetic number, because the mean of its divisors is an integer number (15299658).

Almost surely, 2^81491206 is an apocalyptic number.

81491206 is a deficient number, since it is larger than the sum of its proper divisors (40906058).

81491206 is a wasteful number, since it uses less digits than its factorization.

81491206 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53486.

The product of its (nonzero) digits is 3456, while the sum is 31.

The square root of 81491206 is about 9027.2479748814. The cubic root of 81491206 is about 433.5477283599.

The spelling of 81491206 in words is "eighty-one million, four hundred ninety-one thousand, two hundred six".