21518032 has 20 divisors (see below), whose sum is σ = 43886080. Its totient is φ = 10192608.

The previous prime is 21518027. The next prime is 21518033. The reversal of 21518032 is 23081512.

It is a junction number, because it is equal to n+sod(n) for n = 21517994 and 21518012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21518033) 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, 35088 + ... + 35695.

It is an arithmetic number, because the mean of its divisors is an integer number (2194304).

Almost surely, 2^21518032 is an apocalyptic number.

It is an amenable number.

21518032 is an abundant number, since it is smaller than the sum of its proper divisors (22368048).

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

21518032 is a wasteful number, since it uses less digits than its factorization.

21518032 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 70810 (or 70804 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 22.

The square root of 21518032 is about 4638.7532807857. The cubic root of 21518032 is about 278.1426040618.

Adding to 21518032 its reverse (23081512), we get a palindrome (44599544).

The spelling of 21518032 in words is "twenty-one million, five hundred eighteen thousand, thirty-two".