81423749 has 8 divisors (see below), whose sum is σ = 92688192. Its totient is φ = 70803040.

The previous prime is 81423743. The next prime is 81423779. The reversal of 81423749 is 94732418.

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

It is not a de Polignac number, because 81423749 - 2¹⁶ = 81358213 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81423743) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 160664 + ... + 161169.

It is an arithmetic number, because the mean of its divisors is an integer number (11586024).

Almost surely, 2^81423749 is an apocalyptic number.

It is an amenable number.

81423749 is a deficient number, since it is larger than the sum of its proper divisors (11264443).

81423749 is a wasteful number, since it uses less digits than its factorization.

81423749 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 321867.

The product of its digits is 48384, while the sum is 38.

The square root of 81423749 is about 9023.5109020824. The cubic root of 81423749 is about 433.4280675851.

The spelling of 81423749 in words is "eighty-one million, four hundred twenty-three thousand, seven hundred forty-nine".