81385490 has 8 divisors (see below), whose sum is σ = 146493900. Its totient is φ = 32554192.

The previous prime is 81385481. The next prime is 81385543. The reversal of 81385490 is 9458318.

It can be written as a sum of positive squares in 2 ways, for example, as 81234169 + 151321 = 9013^2 + 389^2 .

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

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4069265 + ... + 4069284.

Almost surely, 2^81385490 is an apocalyptic number.

81385490 is a deficient number, since it is larger than the sum of its proper divisors (65108410).

81385490 is a wasteful number, since it uses less digits than its factorization.

81385490 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8138556.

The product of its (nonzero) digits is 34560, while the sum is 38.

The square root of 81385490 is about 9021.3906910188. The cubic root of 81385490 is about 433.3601712504.

The spelling of 81385490 in words is "eighty-one million, three hundred eighty-five thousand, four hundred ninety".