21985151 has 2 divisors, whose sum is σ = 21985152. Its totient is φ = 21985150.

The previous prime is 21985133. The next prime is 21985153. The reversal of 21985151 is 15158912.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21985151 is a prime.

Together with 21985153, 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 (21985153) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10992575 + 10992576.

It is an arithmetic number, because the mean of its divisors is an integer number (10992576).

Almost surely, 2^21985151 is an apocalyptic number.

21985151 is a deficient number, since it is larger than the sum of its proper divisors (1).

21985151 is an equidigital number, since it uses as much as digits as its factorization.

21985151 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3600, while the sum is 32.

The square root of 21985151 is about 4688.8325839168. The cubic root of 21985151 is about 280.1408772374.

The spelling of 21985151 in words is "twenty-one million, nine hundred eighty-five thousand, one hundred fifty-one".