81397966 has 32 divisors (see below), whose sum is σ = 139023360. Its totient is φ = 35459424.

The previous prime is 81397963. The next prime is 81398027. The reversal of 81397966 is 66979318.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81397963) 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, 46381 + ... + 48103.

It is an arithmetic number, because the mean of its divisors is an integer number (4344480).

Almost surely, 2^81397966 is an apocalyptic number.

81397966 is a deficient number, since it is larger than the sum of its proper divisors (57625394).

81397966 is a wasteful number, since it uses less digits than its factorization.

81397966 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1840.

The product of its digits is 489888, while the sum is 49.

The square root of 81397966 is about 9022.0821321910. The cubic root of 81397966 is about 433.3823141215.

The spelling of 81397966 in words is "eighty-one million, three hundred ninety-seven thousand, nine hundred sixty-six".