21863911 has 2 divisors, whose sum is σ = 21863912. Its totient is φ = 21863910.

The previous prime is 21863903. The next prime is 21863917. The reversal of 21863911 is 11936812.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21863911 - 2³ = 21863903 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21863917) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10931955 + 10931956.

It is an arithmetic number, because the mean of its divisors is an integer number (10931956).

Almost surely, 2^21863911 is an apocalyptic number.

21863911 is a deficient number, since it is larger than the sum of its proper divisors (1).

21863911 is an equidigital number, since it uses as much as digits as its factorization.

21863911 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2592, while the sum is 31.

The square root of 21863911 is about 4675.8861192292. The cubic root of 21863911 is about 279.6249698501.

The spelling of 21863911 in words is "twenty-one million, eight hundred sixty-three thousand, nine hundred eleven".