21321407 has 2 divisors, whose sum is σ = 21321408. Its totient is φ = 21321406.

The previous prime is 21321379. The next prime is 21321431. The reversal of 21321407 is 70412312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21321407 - 2¹⁸ = 21059263 is a prime.

It is a plaindrome in base 16.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21321497) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10660703 + 10660704.

It is an arithmetic number, because the mean of its divisors is an integer number (10660704).

Almost surely, 2^21321407 is an apocalyptic number.

21321407 is a deficient number, since it is larger than the sum of its proper divisors (1).

21321407 is an equidigital number, since it uses as much as digits as its factorization.

21321407 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 336, while the sum is 20.

The square root of 21321407 is about 4617.5109095702. The cubic root of 21321407 is about 277.2928172457.

Adding to 21321407 its reverse (70412312), we get a palindrome (91733719).

The spelling of 21321407 in words is "twenty-one million, three hundred twenty-one thousand, four hundred seven".