133447681 has 4 divisors (see below), whose sum is σ = 133882672. Its totient is φ = 133012692.

The previous prime is 133447673. The next prime is 133447703. The reversal of 133447681 is 186744331.

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 133447681 - 2³ = 133447673 is a prime.

It is a super-2 number, since 2×133447681² = 35616567128555522, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 133447681.

It is not an unprimeable number, because it can be changed into a prime (133447631) 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, 217035 + ... + 217648.

It is an arithmetic number, because the mean of its divisors is an integer number (33470668).

It is a Proth number, since it is equal to 8145 ⋅ 2¹⁴ + 1 and 8145 < 2¹⁴.

Almost surely, 2^133447681 is an apocalyptic number.

It is an amenable number.

133447681 is a deficient number, since it is larger than the sum of its proper divisors (434991).

133447681 is an equidigital number, since it uses as much as digits as its factorization.

133447681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 434990.

The product of its digits is 48384, while the sum is 37.

The square root of 133447681 is about 11551.9557218681. The cubic root of 133447681 is about 511.0189560257.

It can be divided in two parts, 13344 and 7681, that added together give a square (21025 = 145²).

The spelling of 133447681 in words is "one hundred thirty-three million, four hundred forty-seven thousand, six hundred eighty-one".