81420815 has 8 divisors (see below), whose sum is σ = 111662880. Its totient is φ = 55831392.

The previous prime is 81420809. The next prime is 81420827. The reversal of 81420815 is 51802418.

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 81420815 - 2⁴ = 81420799 is a prime.

It is a congruent number.

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 7 ways as a sum of consecutive naturals, for example, 1163120 + ... + 1163189.

It is an arithmetic number, because the mean of its divisors is an integer number (13957860).

Almost surely, 2^81420815 is an apocalyptic number.

81420815 is a deficient number, since it is larger than the sum of its proper divisors (30242065).

81420815 is a wasteful number, since it uses less digits than its factorization.

81420815 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2326321.

The product of its (nonzero) digits is 2560, while the sum is 29.

The square root of 81420815 is about 9023.3483253169. The cubic root of 81420815 is about 433.4228615150.

The spelling of 81420815 in words is "eighty-one million, four hundred twenty thousand, eight hundred fifteen".