81216345 has 32 divisors (see below), whose sum is σ = 150405120. Its totient is φ = 36653760.

The previous prime is 81216341. The next prime is 81216353. The reversal of 81216345 is 54361218.

It is not a de Polignac number, because 81216345 - 2² = 81216341 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is not an unprimeable number, because it can be changed into a prime (81216341) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3400 + ... + 13190.

It is an arithmetic number, because the mean of its divisors is an integer number (4700160).

Almost surely, 2^81216345 is an apocalyptic number.

It is an amenable number.

81216345 is a deficient number, since it is larger than the sum of its proper divisors (69188775).

81216345 is a wasteful number, since it uses less digits than its factorization.

81216345 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9885.

The product of its digits is 5760, while the sum is 30.

The square root of 81216345 is about 9012.0111517907. The cubic root of 81216345 is about 433.0597428176.

The spelling of 81216345 in words is "eighty-one million, two hundred sixteen thousand, three hundred forty-five".