16001221015 has 16 divisors (see below), whose sum is σ = 21894884928. Its totient is φ = 11121209856.

The previous prime is 16001220973. The next prime is 16001221091. The reversal of 16001221015 is 51012210061.

It is a cyclic number.

It is not a de Polignac number, because 16001221015 - 2¹¹ = 16001218967 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 16001220983 and 16001221001.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7239267 + ... + 7241476.

It is an arithmetic number, because the mean of its divisors is an integer number (1368430308).

Almost surely, 2^16001221015 is an apocalyptic number.

16001221015 is a deficient number, since it is larger than the sum of its proper divisors (5893663913).

16001221015 is a wasteful number, since it uses less digits than its factorization.

16001221015 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14480778.

The product of its (nonzero) digits is 120, while the sum is 19.

Adding to 16001221015 its reverse (51012210061), we get a palindrome (67013431076).

It can be divided in two parts, 16001 and 221015, that added together give a triangular number (237016 = T₆₈₈).

The spelling of 16001221015 in words is "sixteen billion, one million, two hundred twenty-one thousand, fifteen".