21111812 has 12 divisors (see below), whose sum is σ = 38890320. Its totient is φ = 10000296.

The previous prime is 21111791. The next prime is 21111821. The reversal of 21111812 is 21811112.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 138818 + ... + 138969.

It is an arithmetic number, because the mean of its divisors is an integer number (3240860).

Almost surely, 2^21111812 is an apocalyptic number.

It is an amenable number.

21111812 is a deficient number, since it is larger than the sum of its proper divisors (17778508).

21111812 is a wasteful number, since it uses less digits than its factorization.

21111812 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 277810 (or 277808 counting only the distinct ones).

The product of its digits is 32, while the sum is 17.

The square root of 21111812 is about 4594.7591884668. The cubic root of 21111812 is about 276.3812032793.

Adding to 21111812 its reverse (21811112), we get a palindrome (42922924).

The spelling of 21111812 in words is "twenty-one million, one hundred eleven thousand, eight hundred twelve".