16409138921 has 4 divisors (see below), whose sum is σ = 18753301632. Its totient is φ = 14064976212.

The previous prime is 16409138903. The next prime is 16409138951. The reversal of 16409138921 is 12983190461.

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.

It is not a de Polignac number, because 16409138921 - 2¹⁰ = 16409137897 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16409138951) 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 3 ways as a sum of consecutive naturals, for example, 1172081345 + ... + 1172081358.

It is an arithmetic number, because the mean of its divisors is an integer number (4688325408).

Almost surely, 2^16409138921 is an apocalyptic number.

It is an amenable number.

16409138921 is a deficient number, since it is larger than the sum of its proper divisors (2344162711).

16409138921 is an equidigital number, since it uses as much as digits as its factorization.

16409138921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2344162710.

The product of its (nonzero) digits is 93312, while the sum is 44.

The spelling of 16409138921 in words is "sixteen billion, four hundred nine million, one hundred thirty-eight thousand, nine hundred twenty-one".