81420245 has 4 divisors (see below), whose sum is σ = 97704300. Its totient is φ = 65136192.

The previous prime is 81420221. The next prime is 81420271. The reversal of 81420245 is 54202418.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 35153041 + 46267204 = 5929^2 + 6802^2 .

It is a cyclic number.

It is not a de Polignac number, because 81420245 - 2⁶ = 81420181 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 (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8142020 + ... + 8142029.

It is an arithmetic number, because the mean of its divisors is an integer number (24426075).

Almost surely, 2^81420245 is an apocalyptic number.

It is an amenable number.

81420245 is a deficient number, since it is larger than the sum of its proper divisors (16284055).

81420245 is a wasteful number, since it uses less digits than its factorization.

81420245 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16284054.

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

The square root of 81420245 is about 9023.3167405339. The cubic root of 81420245 is about 433.4218500963.

The spelling of 81420245 in words is "eighty-one million, four hundred twenty thousand, two hundred forty-five".