21106506201615 has 24 divisors (see below), whose sum is σ = 36588991218000. Its totient is φ = 11255455471104.

The previous prime is 21106506201611. The next prime is 21106506201659. The reversal of 21106506201615 is 51610260560112.

21106506201615 is a `hidden beast` number, since 2 + 1 + 1 + 0 + 6 + 5 + 0 + 620 + 16 + 15 = 666.

It is not a de Polignac number, because 21106506201615 - 2² = 21106506201611 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21106506201615.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21106506201611) 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, 27699865 + ... + 28451634.

It is an arithmetic number, because the mean of its divisors is an integer number (1524541300750).

Almost surely, 2^{21106506201615} is an apocalyptic number.

21106506201615 is a deficient number, since it is larger than the sum of its proper divisors (15482485016385).

21106506201615 is a wasteful number, since it uses less digits than its factorization.

21106506201615 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56159863 (or 56159860 counting only the distinct ones).

The product of its (nonzero) digits is 21600, while the sum is 36.

Adding to 21106506201615 its reverse (51610260560112), we get a palindrome (72716766761727).

The spelling of 21106506201615 in words is "twenty-one trillion, one hundred six billion, five hundred six million, two hundred one thousand, six hundred fifteen".