21135612 has 12 divisors (see below), whose sum is σ = 49316456. Its totient is φ = 7045200.

The previous prime is 21135593. The next prime is 21135613. The reversal of 21135612 is 21653112.

It is a tau number, because it is divible by the number of its divisors (12).

It is a super-2 number, since 2×21135612² = 893428189229088, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21135613) 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, 880639 + ... + 880662.

Almost surely, 2^21135612 is an apocalyptic number.

It is an amenable number.

21135612 is an abundant number, since it is smaller than the sum of its proper divisors (28180844).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21135612 is a wasteful number, since it uses less digits than its factorization.

21135612 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1761308 (or 1761306 counting only the distinct ones).

The product of its digits is 360, while the sum is 21.

The square root of 21135612 is about 4597.3483661781. The cubic root of 21135612 is about 276.4850219752.

Adding to 21135612 its reverse (21653112), we get a palindrome (42788724).

The spelling of 21135612 in words is "twenty-one million, one hundred thirty-five thousand, six hundred twelve".