133749281 has 4 divisors (see below), whose sum is σ = 133785600. Its totient is φ = 133712964.

The previous prime is 133749211. The next prime is 133749331. The reversal of 133749281 is 182947331.

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 a de Polignac number, because none of the positive numbers 2^k-133749281 is a prime.

It is a super-2 number, since 2×133749281² = 35777740336033922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (133749211) 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, 11921 + ... + 20238.

It is an arithmetic number, because the mean of its divisors is an integer number (33446400).

Almost surely, 2^133749281 is an apocalyptic number.

It is an amenable number.

133749281 is a deficient number, since it is larger than the sum of its proper divisors (36319).

133749281 is an equidigital number, since it uses as much as digits as its factorization.

133749281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36318.

The product of its digits is 36288, while the sum is 38.

The square root of 133749281 is about 11565.0024210979. The cubic root of 133749281 is about 511.4036444972.

The spelling of 133749281 in words is "one hundred thirty-three million, seven hundred forty-nine thousand, two hundred eighty-one".