21518450 has 24 divisors (see below), whose sum is σ = 42132720. Its totient is φ = 8154000.

The previous prime is 21518411. The next prime is 21518459. The reversal of 21518450 is 5481512.

It is not an unprimeable number, because it can be changed into a prime (21518459) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 10376 + ... + 12275.

It is an arithmetic number, because the mean of its divisors is an integer number (1755530).

Almost surely, 2^21518450 is an apocalyptic number.

21518450 is a deficient number, since it is larger than the sum of its proper divisors (20614270).

21518450 is a wasteful number, since it uses less digits than its factorization.

21518450 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22682 (or 22677 counting only the distinct ones).

The product of its (nonzero) digits is 1600, while the sum is 26.

The square root of 21518450 is about 4638.7983357762. The cubic root of 21518450 is about 278.1444050762.

Adding to 21518450 its reverse (5481512), we get a palindrome (26999962).

It can be divided in two parts, 2151 and 8450, that added together give a palindrome (10601).

The spelling of 21518450 in words is "twenty-one million, five hundred eighteen thousand, four hundred fifty".