133072721 has 4 divisors (see below), whose sum is σ = 133361844. Its totient is φ = 132783600.

The previous prime is 133072703. The next prime is 133072763. The reversal of 133072721 is 127270331.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 64000000 + 69072721 = 8000^2 + 8311^2 .

It is a cyclic number.

It is not a de Polignac number, because 133072721 - 2⁶ = 133072657 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (133072021) 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, 143870 + ... + 144791.

It is an arithmetic number, because the mean of its divisors is an integer number (33340461).

Almost surely, 2^133072721 is an apocalyptic number.

It is an amenable number.

133072721 is a deficient number, since it is larger than the sum of its proper divisors (289123).

133072721 is an equidigital number, since it uses as much as digits as its factorization.

133072721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 289122.

The product of its (nonzero) digits is 1764, while the sum is 26.

The square root of 133072721 is about 11535.7150190181. The cubic root of 133072721 is about 510.5398883495.

The spelling of 133072721 in words is "one hundred thirty-three million, seventy-two thousand, seven hundred twenty-one".