81278197 has 16 divisors (see below), whose sum is σ = 109130112. Its totient is φ = 58461120.

The previous prime is 81278189. The next prime is 81278209. The reversal of 81278197 is 79187218.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 81278197 - 2³ = 81278189 is a prime.

It is a super-2 number, since 2×81278197² = 13212290615141618, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81278137) 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, 39598 + ... + 41599.

It is an arithmetic number, because the mean of its divisors is an integer number (6820632).

Almost surely, 2^81278197 is an apocalyptic number.

It is an amenable number.

81278197 is a deficient number, since it is larger than the sum of its proper divisors (27851915).

81278197 is a wasteful number, since it uses less digits than its factorization.

81278197 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81228.

The product of its digits is 56448, while the sum is 43.

The square root of 81278197 is about 9015.4421411265. The cubic root of 81278197 is about 433.1696501455.

The spelling of 81278197 in words is "eighty-one million, two hundred seventy-eight thousand, one hundred ninety-seven".