81749013 has 4 divisors (see below), whose sum is σ = 108998688. Its totient is φ = 54499340.

The previous prime is 81749009. The next prime is 81749029. The reversal of 81749013 is 31094718.

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 a cyclic number.

It is not a de Polignac number, because 81749013 - 2² = 81749009 is a prime.

It is a super-2 number, since 2×81749013² = 13365802252948338, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81749033) 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, 13624833 + ... + 13624838.

It is an arithmetic number, because the mean of its divisors is an integer number (27249672).

Almost surely, 2^81749013 is an apocalyptic number.

It is an amenable number.

81749013 is a deficient number, since it is larger than the sum of its proper divisors (27249675).

81749013 is a wasteful number, since it uses less digits than its factorization.

81749013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27249674.

The product of its (nonzero) digits is 6048, while the sum is 33.

The square root of 81749013 is about 9041.5160786231. The cubic root of 81749013 is about 434.0044401281.

The spelling of 81749013 in words is "eighty-one million, seven hundred forty-nine thousand, thirteen".