81210447 has 12 divisors (see below), whose sum is σ = 122404464. Its totient is φ = 51786240.

The previous prime is 81210431. The next prime is 81210457. The reversal of 81210447 is 74401218.

81210447 is a `hidden beast` number, since 8 + 1 + 210 + 447 = 666.

It is not a de Polignac number, because 81210447 - 2⁴ = 81210431 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81210447.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81210457) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 195954 + ... + 196367.

It is an arithmetic number, because the mean of its divisors is an integer number (10200372).

Almost surely, 2^81210447 is an apocalyptic number.

81210447 is a deficient number, since it is larger than the sum of its proper divisors (41194017).

81210447 is a wasteful number, since it uses less digits than its factorization.

81210447 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 392350 (or 392347 counting only the distinct ones).

The product of its (nonzero) digits is 1792, while the sum is 27.

The square root of 81210447 is about 9011.6839158950. The cubic root of 81210447 is about 433.0492595083.

The spelling of 81210447 in words is "eighty-one million, two hundred ten thousand, four hundred forty-seven".