21208754330787 has 4 divisors (see below), whose sum is σ = 28278339107720. Its totient is φ = 14139169553856.

The previous prime is 21208754330693. The next prime is 21208754330789. The reversal of 21208754330787 is 78703345780212.

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

It is not a de Polignac number, because 21208754330787 - 2²⁶ = 21208687221923 is a prime.

It is a super-2 number, since 2×21208754330787² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21208754330789) 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, 3534792388462 + ... + 3534792388467.

It is an arithmetic number, because the mean of its divisors is an integer number (7069584776930).

Almost surely, 2^{21208754330787} is an apocalyptic number.

21208754330787 is a deficient number, since it is larger than the sum of its proper divisors (7069584776933).

21208754330787 is an equidigital number, since it uses as much as digits as its factorization.

21208754330787 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7069584776932.

The product of its (nonzero) digits is 15805440, while the sum is 57.

The spelling of 21208754330787 in words is "twenty-one trillion, two hundred eight billion, seven hundred fifty-four million, three hundred thirty thousand, seven hundred eighty-seven".