21493633 has 16 divisors (see below), whose sum is σ = 26051584. Its totient is φ = 17340480.

The previous prime is 21493621. The next prime is 21493639. The reversal of 21493633 is 33639412.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21493633 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21493595 and 21493604.

It is not an unprimeable number, because it can be changed into a prime (21493639) 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, 6691 + ... + 9367.

It is an arithmetic number, because the mean of its divisors is an integer number (1628224).

Almost surely, 2^21493633 is an apocalyptic number.

21493633 is the 2677-th octagonal number.

It is an amenable number.

21493633 is a deficient number, since it is larger than the sum of its proper divisors (4557951).

21493633 is a wasteful number, since it uses less digits than its factorization.

21493633 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2752.

The product of its digits is 11664, while the sum is 31.

The square root of 21493633 is about 4636.1226256431. The cubic root of 21493633 is about 278.0374369472.

The spelling of 21493633 in words is "twenty-one million, four hundred ninety-three thousand, six hundred thirty-three".