81213473 has 8 divisors (see below), whose sum is σ = 88888800. Its totient is φ = 73586880.

The previous prime is 81213443. The next prime is 81213491. The reversal of 81213473 is 37431218.

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

It is a cyclic number.

It is not a de Polignac number, because 81213473 - 2¹⁰ = 81212449 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81213413) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8648 + ... + 15401.

It is an arithmetic number, because the mean of its divisors is an integer number (11111100).

Almost surely, 2^81213473 is an apocalyptic number.

It is an amenable number.

81213473 is a deficient number, since it is larger than the sum of its proper divisors (7675327).

81213473 is a wasteful number, since it uses less digits than its factorization.

81213473 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24367.

The product of its digits is 4032, while the sum is 29.

The square root of 81213473 is about 9011.8518074811. The cubic root of 81213473 is about 433.0546380888.

The spelling of 81213473 in words is "eighty-one million, two hundred thirteen thousand, four hundred seventy-three".