21931011 has 12 divisors (see below), whose sum is σ = 31782192. Its totient is φ = 14572656.

The previous prime is 21931001. The next prime is 21931027. The reversal of 21931011 is 11013912.

It is not a de Polignac number, because 21931011 - 2¹⁰ = 21929987 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21931001) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 991 + ... + 6696.

It is an arithmetic number, because the mean of its divisors is an integer number (2648516).

Almost surely, 2^21931011 is an apocalyptic number.

21931011 is a deficient number, since it is larger than the sum of its proper divisors (9851181).

21931011 is a wasteful number, since it uses less digits than its factorization.

21931011 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8010 (or 8007 counting only the distinct ones).

The product of its (nonzero) digits is 54, while the sum is 18.

The square root of 21931011 is about 4683.0557331725. The cubic root of 21931011 is about 279.9107325979.

Adding to 21931011 its reverse (11013912), we get a palindrome (32944923).

The spelling of 21931011 in words is "twenty-one million, nine hundred thirty-one thousand, eleven".