21006550015 has 16 divisors (see below), whose sum is σ = 28242715680. Its totient is φ = 14864584320.

The previous prime is 21006550013. The next prime is 21006550027. The reversal of 21006550015 is 51005560012.

It is not a de Polignac number, because 21006550015 - 2¹ = 21006550013 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21006550013) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5159280 + ... + 5163349.

It is an arithmetic number, because the mean of its divisors is an integer number (1765169730).

Almost surely, 2^21006550015 is an apocalyptic number.

21006550015 is a deficient number, since it is larger than the sum of its proper divisors (7236165665).

21006550015 is a wasteful number, since it uses less digits than its factorization.

21006550015 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10322682.

The product of its (nonzero) digits is 1500, while the sum is 25.

The spelling of 21006550015 in words is "twenty-one billion, six million, five hundred fifty thousand, fifteen".