20111005721 has 4 divisors (see below), whose sum is σ = 20111785344. Its totient is φ = 20110226100.

The previous prime is 20111005709. The next prime is 20111005727. The reversal of 20111005721 is 12750011102.

It is a happy number.

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 20111005721 - 2¹⁸ = 20110743577 is a prime.

It is a super-2 number, since 2×20111005721² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20111005693 and 20111005702.

It is not an unprimeable number, because it can be changed into a prime (20111005727) 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, 349745 + ... + 403166.

It is an arithmetic number, because the mean of its divisors is an integer number (5027946336).

Almost surely, 2^20111005721 is an apocalyptic number.

It is an amenable number.

20111005721 is a deficient number, since it is larger than the sum of its proper divisors (779623).

20111005721 is an equidigital number, since it uses as much as digits as its factorization.

20111005721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 779622.

The product of its (nonzero) digits is 140, while the sum is 20.

Adding to 20111005721 its reverse (12750011102), we get a palindrome (32861016823).

The spelling of 20111005721 in words is "twenty billion, one hundred eleven million, five thousand, seven hundred twenty-one".