81870305 has 16 divisors (see below), whose sum is σ = 107956800. Its totient is φ = 59108160.

The previous prime is 81870293. The next prime is 81870311. The reversal of 81870305 is 50307818.

It is not a de Polignac number, because 81870305 - 2⁴ = 81870289 is a prime.

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

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2291 + ... + 12999.

It is an arithmetic number, because the mean of its divisors is an integer number (6747300).

Almost surely, 2^81870305 is an apocalyptic number.

It is an amenable number.

81870305 is a deficient number, since it is larger than the sum of its proper divisors (26086495).

81870305 is a wasteful number, since it uses less digits than its factorization.

81870305 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10864.

The product of its (nonzero) digits is 6720, while the sum is 32.

The square root of 81870305 is about 9048.2210958840. The cubic root of 81870305 is about 434.2189799382.

The spelling of 81870305 in words is "eighty-one million, eight hundred seventy thousand, three hundred five".