81224857 has 4 divisors (see below), whose sum is σ = 92828416. Its totient is φ = 69621300.

The previous prime is 81224839. The next prime is 81224881. The reversal of 81224857 is 75842218.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 81224857 - 2¹¹ = 81222809 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81224257) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5801769 + ... + 5801782.

It is an arithmetic number, because the mean of its divisors is an integer number (23207104).

Almost surely, 2^81224857 is an apocalyptic number.

It is an amenable number.

81224857 is a deficient number, since it is larger than the sum of its proper divisors (11603559).

81224857 is a wasteful number, since it uses less digits than its factorization.

81224857 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11603558.

The product of its digits is 35840, while the sum is 37.

The square root of 81224857 is about 9012.4833980430. The cubic root of 81224857 is about 433.0748714462.

The spelling of 81224857 in words is "eighty-one million, two hundred twenty-four thousand, eight hundred fifty-seven".