81390542 has 4 divisors (see below), whose sum is σ = 122085816. Its totient is φ = 40695270.

The previous prime is 81390541. The next prime is 81390553. The reversal of 81390542 is 24509318.

It is a semiprime because it is the product of two primes.

It is a junction number, because it is equal to n+sod(n) for n = 81390499 and 81390508.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81390541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20347634 + ... + 20347637.

It is an arithmetic number, because the mean of its divisors is an integer number (30521454).

Almost surely, 2^81390542 is an apocalyptic number.

81390542 is a deficient number, since it is larger than the sum of its proper divisors (40695274).

81390542 is a wasteful number, since it uses less digits than its factorization.

81390542 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40695273.

The product of its (nonzero) digits is 8640, while the sum is 32.

The square root of 81390542 is about 9021.6706878493. The cubic root of 81390542 is about 433.3691380014.

The spelling of 81390542 in words is "eighty-one million, three hundred ninety thousand, five hundred forty-two".