16456331521 has 4 divisors (see below), whose sum is σ = 18807236032. Its totient is φ = 14105427012.

The previous prime is 16456331497. The next prime is 16456331533. The reversal of 16456331521 is 12513365461.

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: 12513365461 = 12401 ⋅1009061.

It is a cyclic number.

It is not a de Polignac number, because 16456331521 - 2⁷ = 16456331393 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16456335521) 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, 1175452245 + ... + 1175452258.

It is an arithmetic number, because the mean of its divisors is an integer number (4701809008).

Almost surely, 2^16456331521 is an apocalyptic number.

It is an amenable number.

16456331521 is a deficient number, since it is larger than the sum of its proper divisors (2350904511).

16456331521 is an equidigital number, since it uses as much as digits as its factorization.

16456331521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2350904510.

The product of its digits is 64800, while the sum is 37.

Adding to 16456331521 its reverse (12513365461), we get a palindrome (28969696982).

The spelling of 16456331521 in words is "sixteen billion, four hundred fifty-six million, three hundred thirty-one thousand, five hundred twenty-one".