16431421 has 2 divisors, whose sum is σ = 16431422. Its totient is φ = 16431420.

The previous prime is 16431419. The next prime is 16431449. The reversal of 16431421 is 12413461.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16112196 + 319225 = 4014^2 + 565^2 .

It is an emirp because it is prime and its reverse (12413461) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 16431421 - 2¹ = 16431419 is a prime.

Together with 16431419, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 16431392 and 16431401.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16431221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8215710 + 8215711.

It is an arithmetic number, because the mean of its divisors is an integer number (8215711).

Almost surely, 2^16431421 is an apocalyptic number.

It is an amenable number.

16431421 is a deficient number, since it is larger than the sum of its proper divisors (1).

16431421 is an equidigital number, since it uses as much as digits as its factorization.

16431421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 576, while the sum is 22.

The square root of 16431421 is about 4053.5689213334. The cubic root of 16431421 is about 254.2289718198.

Adding to 16431421 its reverse (12413461), we get a palindrome (28844882).

The spelling of 16431421 in words is "sixteen million, four hundred thirty-one thousand, four hundred twenty-one".