81400387 has 8 divisors (see below), whose sum is σ = 82272960. Its totient is φ = 80531880.

The previous prime is 81400349. The next prime is 81400393. The reversal of 81400387 is 78300418.

It is a happy number.

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 81400387 - 2¹⁵ = 81367619 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81400307) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 54148 + ... + 55630.

It is an arithmetic number, because the mean of its divisors is an integer number (10284120).

Almost surely, 2^81400387 is an apocalyptic number.

81400387 is a deficient number, since it is larger than the sum of its proper divisors (872573).

81400387 is a wasteful number, since it uses less digits than its factorization.

81400387 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2033.

The product of its (nonzero) digits is 5376, while the sum is 31.

The square root of 81400387 is about 9022.2163019959. The cubic root of 81400387 is about 433.3866107406.

Adding to 81400387 its sum of digits (31), we get a palindrome (81400418).

The spelling of 81400387 in words is "eighty-one million, four hundred thousand, three hundred eighty-seven".