21108723551737 has 4 divisors (see below), whose sum is σ = 21113712618496. Its totient is φ = 21103734484980.

The previous prime is 21108723551719. The next prime is 21108723551753. The reversal of 21108723551737 is 73715532780112.

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 a de Polignac number, because none of the positive numbers 2^k-21108723551737 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21108723551537) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2494527033 + ... + 2494535494.

It is an arithmetic number, because the mean of its divisors is an integer number (5278428154624).

Almost surely, 2^{21108723551737} is an apocalyptic number.

It is an amenable number.

21108723551737 is a deficient number, since it is larger than the sum of its proper divisors (4989066759).

21108723551737 is an equidigital number, since it uses as much as digits as its factorization.

21108723551737 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4989066758.

The product of its (nonzero) digits is 2469600, while the sum is 52.

The spelling of 21108723551737 in words is "twenty-one trillion, one hundred eight billion, seven hundred twenty-three million, five hundred fifty-one thousand, seven hundred thirty-seven".