16403421 has 16 divisors (see below), whose sum is σ = 22296384. Its totient is φ = 10725504.

The previous prime is 16403417. The next prime is 16403437. The reversal of 16403421 is 12430461.

It is not a de Polignac number, because 16403421 - 2² = 16403417 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16403461) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 43791 + ... + 44163.

It is an arithmetic number, because the mean of its divisors is an integer number (1393524).

Almost surely, 2^16403421 is an apocalyptic number.

It is an amenable number.

16403421 is a deficient number, since it is larger than the sum of its proper divisors (5892963).

16403421 is a wasteful number, since it uses less digits than its factorization.

16403421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 620.

The product of its (nonzero) digits is 576, while the sum is 21.

The square root of 16403421 is about 4050.1137021076. The cubic root of 16403421 is about 254.0844832325.

Adding to 16403421 its reverse (12430461), we get a palindrome (28833882).

The spelling of 16403421 in words is "sixteen million, four hundred three thousand, four hundred twenty-one".