21018416 has 10 divisors (see below), whose sum is σ = 40723212. Its totient is φ = 10509200.

The previous prime is 21018407. The next prime is 21018461. The reversal of 21018416 is 61481012.

It is a super-2 number, since 2×21018416² = 883547622298112, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21018391 and 21018400.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 656810 + ... + 656841.

Almost surely, 2^21018416 is an apocalyptic number.

It is an amenable number.

21018416 is a deficient number, since it is larger than the sum of its proper divisors (19704796).

21018416 is a wasteful number, since it uses less digits than its factorization.

21018416 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1313659 (or 1313653 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 23.

The square root of 21018416 is about 4584.5846049560. The cubic root of 21018416 is about 275.9730422456.

Adding to 21018416 its reverse (61481012), we get a palindrome (82499428).

The spelling of 21018416 in words is "twenty-one million, eighteen thousand, four hundred sixteen".