21355507 has 2 divisors, whose sum is σ = 21355508. Its totient is φ = 21355506.

The previous prime is 21355501. The next prime is 21355511. The reversal of 21355507 is 70555312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21355507 - 2¹¹ = 21353459 is a prime.

It is not a weakly prime, because it can be changed into another prime (21355501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10677753 + 10677754.

It is an arithmetic number, because the mean of its divisors is an integer number (10677754).

Almost surely, 2^21355507 is an apocalyptic number.

21355507 is a deficient number, since it is larger than the sum of its proper divisors (1).

21355507 is an equidigital number, since it uses as much as digits as its factorization.

21355507 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5250, while the sum is 28.

The square root of 21355507 is about 4621.2018999390. The cubic root of 21355507 is about 277.4405662290.

It can be divided in two parts, 21 and 355507, that multiplied together give a palindrome (7465647).

The spelling of 21355507 in words is "twenty-one million, three hundred fifty-five thousand, five hundred seven".