21400415 has 4 divisors (see below), whose sum is σ = 25680504. Its totient is φ = 17120328.

The previous prime is 21400397. The next prime is 21400417. The reversal of 21400415 is 51400412.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21400415 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21400393 and 21400402.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21400417) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2140037 + ... + 2140046.

It is an arithmetic number, because the mean of its divisors is an integer number (6420126).

Almost surely, 2^21400415 is an apocalyptic number.

21400415 is a deficient number, since it is larger than the sum of its proper divisors (4280089).

21400415 is an equidigital number, since it uses as much as digits as its factorization.

21400415 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4280088.

The product of its (nonzero) digits is 160, while the sum is 17.

The square root of 21400415 is about 4626.0582573072. The cubic root of 21400415 is about 277.6349045118.

Adding to 21400415 its reverse (51400412), we get a palindrome (72800827).

The spelling of 21400415 in words is "twenty-one million, four hundred thousand, four hundred fifteen".