81405242 has 8 divisors (see below), whose sum is σ = 122148000. Its totient is φ = 40689244.

The previous prime is 81405229. The next prime is 81405301. The reversal of 81405242 is 24250418.

It is a happy number.

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

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5009 + ... + 13707.

It is an arithmetic number, because the mean of its divisors is an integer number (15268500).

Almost surely, 2^81405242 is an apocalyptic number.

81405242 is a deficient number, since it is larger than the sum of its proper divisors (40742758).

81405242 is a wasteful number, since it uses less digits than its factorization.

81405242 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13380.

The product of its (nonzero) digits is 2560, while the sum is 26.

The square root of 81405242 is about 9022.4853560424. The cubic root of 81405242 is about 433.3952267937.

The spelling of 81405242 in words is "eighty-one million, four hundred five thousand, two hundred forty-two".