20911231 has 4 divisors (see below), whose sum is σ = 22812264. Its totient is φ = 19010200.

The previous prime is 20911223. The next prime is 20911243. The reversal of 20911231 is 13211902.

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

It is not a de Polignac number, because 20911231 - 2³ = 20911223 is a prime.

It is a super-2 number, since 2×20911231² = 874559163870722, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20911199 and 20911208.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20911211) 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, 950500 + ... + 950521.

It is an arithmetic number, because the mean of its divisors is an integer number (5703066).

Almost surely, 2^20911231 is an apocalyptic number.

20911231 is a deficient number, since it is larger than the sum of its proper divisors (1901033).

20911231 is a wasteful number, since it uses less digits than its factorization.

20911231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1901032.

The product of its (nonzero) digits is 108, while the sum is 19.

The square root of 20911231 is about 4572.8799459422. The cubic root of 20911231 is about 275.5031274246.

The spelling of 20911231 in words is "twenty million, nine hundred eleven thousand, two hundred thirty-one".