21535138 has 8 divisors (see below), whose sum is σ = 32325120. Its totient is φ = 10760100.

The previous prime is 21535123. The next prime is 21535169. The reversal of 21535138 is 83153512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1143 + ... + 6661.

It is an arithmetic number, because the mean of its divisors is an integer number (4040640).

Almost surely, 2^21535138 is an apocalyptic number.

21535138 is a deficient number, since it is larger than the sum of its proper divisors (10789982).

21535138 is a wasteful number, since it uses less digits than its factorization.

21535138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7472.

The product of its digits is 3600, while the sum is 28.

The square root of 21535138 is about 4640.5967288701. The cubic root of 21535138 is about 278.2162887302.

It can be divided in two parts, 215 and 35138, that added together give a palindrome (35353).

The spelling of 21535138 in words is "twenty-one million, five hundred thirty-five thousand, one hundred thirty-eight".