81213475 has 24 divisors (see below), whose sum is σ = 115483680. Its totient is φ = 55499520.

The previous prime is 81213443. The next prime is 81213491. The reversal of 81213475 is 57431218.

It is not a de Polignac number, because 81213475 - 2⁵ = 81213443 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 67479 + ... + 68671.

It is an arithmetic number, because the mean of its divisors is an integer number (4811820).

Almost surely, 2^81213475 is an apocalyptic number.

81213475 is a deficient number, since it is larger than the sum of its proper divisors (34270205).

81213475 is a wasteful number, since it uses less digits than its factorization.

81213475 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1599 (or 1594 counting only the distinct ones).

The product of its digits is 6720, while the sum is 31.

The square root of 81213475 is about 9011.8519184461. The cubic root of 81213475 is about 433.0546416437.

The spelling of 81213475 in words is "eighty-one million, two hundred thirteen thousand, four hundred seventy-five".