21042512 has 20 divisors (see below), whose sum is σ = 41765556. Its totient is φ = 10264320.

The previous prime is 21042491. The next prime is 21042533. The reversal of 21042512 is 21524012.

It is an interprime number because it is at equal distance from previous prime (21042491) and next prime (21042533).

It can be written as a sum of positive squares in 2 ways, for example, as 12138256 + 8904256 = 3484^2 + 2984^2 .

It is a super-2 number, since 2×21042512² = 885574622540288, which contains 22 as substring.

It is a congruent number.

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, 15383 + ... + 16694.

Almost surely, 2^21042512 is an apocalyptic number.

It is an amenable number.

21042512 is a deficient number, since it is larger than the sum of its proper divisors (20723044).

21042512 is a wasteful number, since it uses less digits than its factorization.

21042512 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32126 (or 32120 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 17.

The square root of 21042512 is about 4587.2117893117. The cubic root of 21042512 is about 276.0784626043.

Adding to 21042512 its reverse (21524012), we get a palindrome (42566524).

The spelling of 21042512 in words is "twenty-one million, forty-two thousand, five hundred twelve".