21355967 has 2 divisors, whose sum is σ = 21355968. Its totient is φ = 21355966.

The previous prime is 21355963. The next prime is 21355969. The reversal of 21355967 is 76955312.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21355967 - 2² = 21355963 is a prime.

Together with 21355969, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21355967.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21355963) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10677983 + 10677984.

It is an arithmetic number, because the mean of its divisors is an integer number (10677984).

Almost surely, 2^21355967 is an apocalyptic number.

21355967 is a deficient number, since it is larger than the sum of its proper divisors (1).

21355967 is an equidigital number, since it uses as much as digits as its factorization.

21355967 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 56700, while the sum is 38.

The square root of 21355967 is about 4621.2516702729. The cubic root of 21355967 is about 277.4425582482.

It can be divided in two parts, 21355 and 967, that added together give a palindrome (22322).

The spelling of 21355967 in words is "twenty-one million, three hundred fifty-five thousand, nine hundred sixty-seven".