21438536 has 32 divisors (see below), whose sum is σ = 48360000. Its totient is φ = 8703936.

The previous prime is 21438499. The next prime is 21438541. The reversal of 21438536 is 63583412.

It is a super-2 number, since 2×21438536² = 919221651646592, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9011 + ... + 11138.

It is an arithmetic number, because the mean of its divisors is an integer number (1511250).

Almost surely, 2^21438536 is an apocalyptic number.

It is an amenable number.

21438536 is an abundant number, since it is smaller than the sum of its proper divisors (26921464).

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

21438536 is a wasteful number, since it uses less digits than its factorization.

21438536 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20181 (or 20177 counting only the distinct ones).

The product of its digits is 17280, while the sum is 32.

The square root of 21438536 is about 4630.1766704954. The cubic root of 21438536 is about 277.7996589815.

The spelling of 21438536 in words is "twenty-one million, four hundred thirty-eight thousand, five hundred thirty-six".