133399681 has 4 divisors (see below), whose sum is σ = 137999700. Its totient is φ = 128799664.

The previous prime is 133399579. The next prime is 133399709. The reversal of 133399681 is 186993331.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 186993331 = 7 ⋅26713333.

It can be written as a sum of positive squares in 2 ways, for example, as 27206656 + 106193025 = 5216^2 + 10305^2 .

It is a cyclic number.

It is not a de Polignac number, because 133399681 - 2¹¹ = 133397633 is a prime.

It is a super-2 number, since 2×133399681² = 35590949781803522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (133399481) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2299966 + ... + 2300023.

It is an arithmetic number, because the mean of its divisors is an integer number (34499925).

Almost surely, 2^133399681 is an apocalyptic number.

It is an amenable number.

133399681 is a deficient number, since it is larger than the sum of its proper divisors (4600019).

133399681 is an equidigital number, since it uses as much as digits as its factorization.

133399681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4600018.

The product of its digits is 104976, while the sum is 43.

The square root of 133399681 is about 11549.8779647233. The cubic root of 133399681 is about 510.9576789488.

The spelling of 133399681 in words is "one hundred thirty-three million, three hundred ninety-nine thousand, six hundred eighty-one".