21401216 has 16 divisors (see below), whose sum is σ = 42635490. Its totient is φ = 10700544.

The previous prime is 21401203. The next prime is 21401251. The reversal of 21401216 is 61210412.

It can be written as a sum of positive squares in only one way, i.e., 16974400 + 4426816 = 4120^2 + 2104^2 .

It is a tau number, because it is divible by the number of its divisors (16).

It is a junction number, because it is equal to n+sod(n) for n = 21401194 and 21401203.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83471 + ... + 83726.

Almost surely, 2^21401216 is an apocalyptic number.

It is an amenable number.

21401216 is a deficient number, since it is larger than the sum of its proper divisors (21234274).

21401216 is an equidigital number, since it uses as much as digits as its factorization.

21401216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 167211 (or 167199 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 17.

The square root of 21401216 is about 4626.1448312823. The cubic root of 21401216 is about 277.6383683509.

Adding to 21401216 its reverse (61210412), we get a palindrome (82611628).

The spelling of 21401216 in words is "twenty-one million, four hundred one thousand, two hundred sixteen".