21218517432 has 96 divisors (see below), whose sum is σ = 68563270800. Its totient is φ = 6062430528.

The previous prime is 21218517413. The next prime is 21218517503. The reversal of 21218517432 is 23471581212.

21218517432 is a `hidden beast` number, since 2 + 1 + 218 + 5 + 1 + 7 + 432 = 666.

It is a super-3 number, since 3×21218517432³ (a number of 32 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 991803 + ... + 1012970.

Almost surely, 2^21218517432 is an apocalyptic number.

It is an amenable number.

21218517432 is an abundant number, since it is smaller than the sum of its proper divisors (47344753368).

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

21218517432 is a wasteful number, since it uses less digits than its factorization.

21218517432 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2004802 (or 2004785 counting only the distinct ones).

The product of its digits is 26880, while the sum is 36.

The spelling of 21218517432 in words is "twenty-one billion, two hundred eighteen million, five hundred seventeen thousand, four hundred thirty-two".