21401407 has 2 divisors, whose sum is σ = 21401408. Its totient is φ = 21401406.

The previous prime is 21401399. The next prime is 21401417. The reversal of 21401407 is 70410412.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21401407 - 2³ = 21401399 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21401417) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10700703 + 10700704.

It is an arithmetic number, because the mean of its divisors is an integer number (10700704).

Almost surely, 2^21401407 is an apocalyptic number.

21401407 is a deficient number, since it is larger than the sum of its proper divisors (1).

21401407 is an equidigital number, since it uses as much as digits as its factorization.

21401407 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 224, while the sum is 19.

The square root of 21401407 is about 4626.1654747750. The cubic root of 21401407 is about 277.6391942973.

Adding to 21401407 its reverse (70410412), we get a palindrome (91811819).

The spelling of 21401407 in words is "twenty-one million, four hundred one thousand, four hundred seven".