21887351 has 2 divisors, whose sum is σ = 21887352. Its totient is φ = 21887350.

The previous prime is 21887339. The next prime is 21887353. The reversal of 21887351 is 15378812.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21887351 - 2⁶ = 21887287 is a prime.

It is a super-2 number, since 2×21887351² = 958112267594402, which contains 22 as substring.

Together with 21887353, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21887353) 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, 10943675 + 10943676.

It is an arithmetic number, because the mean of its divisors is an integer number (10943676).

Almost surely, 2^21887351 is an apocalyptic number.

21887351 is a deficient number, since it is larger than the sum of its proper divisors (1).

21887351 is an equidigital number, since it uses as much as digits as its factorization.

21887351 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 13440, while the sum is 35.

The square root of 21887351 is about 4678.3919245826. The cubic root of 21887351 is about 279.7248615299.

The spelling of 21887351 in words is "twenty-one million, eight hundred eighty-seven thousand, three hundred fifty-one".