133873307721521 has 2 divisors, whose sum is σ = 133873307721522. Its totient is φ = 133873307721520.

The previous prime is 133873307721431. The next prime is 133873307721523. The reversal of 133873307721521 is 125127703378331.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 107751354712225 + 26121953009296 = 10380335^2 + 5110964^2 .

It is an emirp because it is prime and its reverse (125127703378331) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-133873307721521 is a prime.

Together with 133873307721523, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (133873307721523) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 66936653860760 + 66936653860761.

It is an arithmetic number, because the mean of its divisors is an integer number (66936653860761).

Almost surely, 2^{133873307721521} is an apocalyptic number.

It is an amenable number.

133873307721521 is a deficient number, since it is larger than the sum of its proper divisors (1).

133873307721521 is an equidigital number, since it uses as much as digits as its factorization.

133873307721521 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4445280, while the sum is 53.

The spelling of 133873307721521 in words is "one hundred thirty-three trillion, eight hundred seventy-three billion, three hundred seven million, seven hundred twenty-one thousand, five hundred twenty-one".