16400421 has 8 divisors (see below), whose sum is σ = 24296960. Its totient is φ = 10933596.

The previous prime is 16400413. The next prime is 16400429. The reversal of 16400421 is 12400461.

16400421 is a `hidden beast` number, since 1 + 640 + 0 + 4 + 21 = 666.

It is an interprime number because it is at equal distance from previous prime (16400413) and next prime (16400429).

It is not a de Polignac number, because 16400421 - 2³ = 16400413 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 16400394 and 16400403.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16400429) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 303685 + ... + 303738.

It is an arithmetic number, because the mean of its divisors is an integer number (3037120).

Almost surely, 2^16400421 is an apocalyptic number.

It is an amenable number.

16400421 is a deficient number, since it is larger than the sum of its proper divisors (7896539).

16400421 is an equidigital number, since it uses as much as digits as its factorization.

16400421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 607432 (or 607426 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

The square root of 16400421 is about 4049.7433251998. The cubic root of 16400421 is about 254.0689925629.

Adding to 16400421 its reverse (12400461), we get a palindrome (28800882).

It can be divided in two parts, 164004 and 21, that added together give a square (164025 = 405²).

The spelling of 16400421 in words is "sixteen million, four hundred thousand, four hundred twenty-one".