81563423 has 4 divisors (see below), whose sum is σ = 81581928. Its totient is φ = 81544920.

The previous prime is 81563381. The next prime is 81563477. The reversal of 81563423 is 32436518.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 32436518 = 2 ⋅16218259.

It is a cyclic number.

It is not a de Polignac number, because 81563423 - 2¹² = 81559327 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81563423.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81563483) 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, 1613 + ... + 12873.

It is an arithmetic number, because the mean of its divisors is an integer number (20395482).

Almost surely, 2^81563423 is an apocalyptic number.

81563423 is a deficient number, since it is larger than the sum of its proper divisors (18505).

81563423 is a wasteful number, since it uses less digits than its factorization.

81563423 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18504.

The product of its digits is 17280, while the sum is 32.

The square root of 81563423 is about 9031.2470346016. The cubic root of 81563423 is about 433.6757596475.

The spelling of 81563423 in words is "eighty-one million, five hundred sixty-three thousand, four hundred twenty-three".