21402417 has 8 divisors (see below), whose sum is σ = 30038560. Its totient is φ = 13517280.

The previous prime is 21402401. The next prime is 21402419. The reversal of 21402417 is 71420412.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21402417 - 2⁴ = 21402401 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21402393 and 21402402.

It is not an unprimeable number, because it can be changed into a prime (21402419) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 187684 + ... + 187797.

It is an arithmetic number, because the mean of its divisors is an integer number (3754820).

Almost surely, 2^21402417 is an apocalyptic number.

It is an amenable number.

21402417 is a deficient number, since it is larger than the sum of its proper divisors (8636143).

21402417 is a wasteful number, since it uses less digits than its factorization.

21402417 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 375503.

The product of its (nonzero) digits is 448, while the sum is 21.

The square root of 21402417 is about 4626.2746351681. The cubic root of 21402417 is about 277.6435617855.

Adding to 21402417 its reverse (71420412), we get a palindrome (92822829).

The spelling of 21402417 in words is "twenty-one million, four hundred two thousand, four hundred seventeen".