21516231601505 has 16 divisors (see below), whose sum is σ = 25831885002240. Its totient is φ = 17204715335808.

The previous prime is 21516231601493. The next prime is 21516231601507. The reversal of 21516231601505 is 50510613261512.

It is a cyclic number.

It is not a de Polignac number, because 21516231601505 - 2³⁰ = 21515157859681 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21516231601507) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 127956014 + ... + 128124056.

It is an arithmetic number, because the mean of its divisors is an integer number (1614492812640).

Almost surely, 2^{21516231601505} is an apocalyptic number.

It is an amenable number.

21516231601505 is a deficient number, since it is larger than the sum of its proper divisors (4315653400735).

21516231601505 is a wasteful number, since it uses less digits than its factorization.

21516231601505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 180200.

The product of its (nonzero) digits is 54000, while the sum is 38.

The spelling of 21516231601505 in words is "twenty-one trillion, five hundred sixteen billion, two hundred thirty-one million, six hundred one thousand, five hundred five".