81749438 has 8 divisors (see below), whose sum is σ = 129078120. Its totient is φ = 38723400.

The previous prime is 81749431. The next prime is 81749441. The reversal of 81749438 is 83494718.

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

It is a super-2 number, since 2×81749438² = 13365941226631688, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81749431) 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, 1075613 + ... + 1075688.

It is an arithmetic number, because the mean of its divisors is an integer number (16134765).

Almost surely, 2^81749438 is an apocalyptic number.

81749438 is a deficient number, since it is larger than the sum of its proper divisors (47328682).

81749438 is a wasteful number, since it uses less digits than its factorization.

81749438 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2151322.

The product of its digits is 193536, while the sum is 44.

The square root of 81749438 is about 9041.5395812881. The cubic root of 81749438 is about 434.0051922333.

The spelling of 81749438 in words is "eighty-one million, seven hundred forty-nine thousand, four hundred thirty-eight".