21766351 has 2 divisors, whose sum is σ = 21766352. Its totient is φ = 21766350.

The previous prime is 21766321. The next prime is 21766363. The reversal of 21766351 is 15366712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21766351 - 2⁹ = 21765839 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21766301) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10883175 + 10883176.

It is an arithmetic number, because the mean of its divisors is an integer number (10883176).

Almost surely, 2^21766351 is an apocalyptic number.

21766351 is a deficient number, since it is larger than the sum of its proper divisors (1).

21766351 is an equidigital number, since it uses as much as digits as its factorization.

21766351 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7560, while the sum is 31.

The square root of 21766351 is about 4665.4422084085. The cubic root of 21766351 is about 279.2084403912.

The spelling of 21766351 in words is "twenty-one million, seven hundred sixty-six thousand, three hundred fifty-one".