21534138 has 24 divisors (see below), whose sum is σ = 49402548. Its totient is φ = 6755712.

The previous prime is 21534089. The next prime is 21534151. The reversal of 21534138 is 83143512.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 20548089 + 986049 = 4533^2 + 993^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 34881 + ... + 35492.

Almost surely, 2^21534138 is an apocalyptic number.

21534138 is an abundant number, since it is smaller than the sum of its proper divisors (27868410).

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

21534138 is a wasteful number, since it uses less digits than its factorization.

21534138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 70398 (or 70395 counting only the distinct ones).

The product of its digits is 2880, while the sum is 27.

The square root of 21534138 is about 4640.4889828551. The cubic root of 21534138 is about 278.2119822708.

The spelling of 21534138 in words is "twenty-one million, five hundred thirty-four thousand, one hundred thirty-eight".