16440266521 has 4 divisors (see below), whose sum is σ = 18788876032. Its totient is φ = 14091657012.

The previous prime is 16440266509. The next prime is 16440266543. The reversal of 16440266521 is 12566204461.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12566204461 = 1627 ⋅7723543.

It is a cyclic number.

It is not a de Polignac number, because 16440266521 - 2²⁷ = 16306048793 is a prime.

It is a super-3 number, since 3×16440266521³ (a number of 32 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16440266501) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1174304745 + ... + 1174304758.

It is an arithmetic number, because the mean of its divisors is an integer number (4697219008).

Almost surely, 2^16440266521 is an apocalyptic number.

It is an amenable number.

16440266521 is a deficient number, since it is larger than the sum of its proper divisors (2348609511).

16440266521 is an equidigital number, since it uses as much as digits as its factorization.

16440266521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2348609510.

The product of its (nonzero) digits is 69120, while the sum is 37.

The spelling of 16440266521 in words is "sixteen billion, four hundred forty million, two hundred sixty-six thousand, five hundred twenty-one".