20721394033 has 4 divisors (see below), whose sum is σ = 20983690240. Its totient is φ = 20459097828.

The previous prime is 20721394021. The next prime is 20721394039. The reversal of 20721394033 is 33049312702.

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 20721394033 - 2²¹ = 20719296881 is a prime.

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 20721394033.

It is not an unprimeable number, because it can be changed into a prime (20721394039) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 131147985 + ... + 131148142.

It is an arithmetic number, because the mean of its divisors is an integer number (5245922560).

Almost surely, 2^20721394033 is an apocalyptic number.

It is an amenable number.

20721394033 is a deficient number, since it is larger than the sum of its proper divisors (262296207).

20721394033 is an equidigital number, since it uses as much as digits as its factorization.

20721394033 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 262296206.

The product of its (nonzero) digits is 27216, while the sum is 34.

The spelling of 20721394033 in words is "twenty billion, seven hundred twenty-one million, three hundred ninety-four thousand, thirty-three".