21516129 has 12 divisors (see below), whose sum is σ = 31919316. Its totient is φ = 13956192.

The previous prime is 21516127. The next prime is 21516137. The reversal of 21516129 is 92161512.

21516129 is a `hidden beast` number, since 21 + 516 + 129 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 13307904 + 8208225 = 3648^2 + 2865^2 .

It is not a de Polignac number, because 21516129 - 2¹ = 21516127 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21516127) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 31974 + ... + 32639.

It is an arithmetic number, because the mean of its divisors is an integer number (2659943).

Almost surely, 2^21516129 is an apocalyptic number.

It is an amenable number.

21516129 is a deficient number, since it is larger than the sum of its proper divisors (10403187).

21516129 is a wasteful number, since it uses less digits than its factorization.

21516129 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 64656 (or 64653 counting only the distinct ones).

The product of its digits is 1080, while the sum is 27.

The square root of 21516129 is about 4638.5481564817. The cubic root of 21516129 is about 278.1344044120.

The spelling of 21516129 in words is "twenty-one million, five hundred sixteen thousand, one hundred twenty-nine".