21135015 has 24 divisors (see below), whose sum is σ = 39965328. Its totient is φ = 10247040.

The previous prime is 21135013. The next prime is 21135031. The reversal of 21135015 is 51053112.

It is not a de Polignac number, because 21135015 - 2¹ = 21135013 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21135013) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 20854 + ... + 21843.

It is an arithmetic number, because the mean of its divisors is an integer number (1665222).

Almost surely, 2^21135015 is an apocalyptic number.

21135015 is a deficient number, since it is larger than the sum of its proper divisors (18830313).

21135015 is a wasteful number, since it uses less digits than its factorization.

21135015 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42719 (or 42716 counting only the distinct ones).

The product of its (nonzero) digits is 150, while the sum is 18.

The square root of 21135015 is about 4597.2834369875. The cubic root of 21135015 is about 276.4824187368.

Adding to 21135015 its reverse (51053112), we get a palindrome (72188127).

The spelling of 21135015 in words is "twenty-one million, one hundred thirty-five thousand, fifteen".