21061911 has 16 divisors (see below), whose sum is σ = 30330720. Its totient is φ = 12923520.

The previous prime is 21061907. The next prime is 21061949. The reversal of 21061911 is 11916012.

It is not a de Polignac number, because 21061911 - 2² = 21061907 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21061981) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 19321 + ... + 20381.

It is an arithmetic number, because the mean of its divisors is an integer number (1895670).

Almost surely, 2^21061911 is an apocalyptic number.

21061911 is a deficient number, since it is larger than the sum of its proper divisors (9268809).

21061911 is a wasteful number, since it uses less digits than its factorization.

21061911 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1586.

The product of its (nonzero) digits is 108, while the sum is 21.

The square root of 21061911 is about 4589.3257674739. The cubic root of 21061911 is about 276.1632750569.

Adding to 21061911 its reverse (11916012), we get a palindrome (32977923).

The spelling of 21061911 in words is "twenty-one million, sixty-one thousand, nine hundred eleven".