21951073 has 2 divisors, whose sum is σ = 21951074. Its totient is φ = 21951072.

The previous prime is 21951071. The next prime is 21951079. The reversal of 21951073 is 37015912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21233664 + 717409 = 4608^2 + 847^2 .

It is a cyclic number.

It is not a de Polignac number, because 21951073 - 2¹ = 21951071 is a prime.

Together with 21951071, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21951071) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10975536 + 10975537.

It is an arithmetic number, because the mean of its divisors is an integer number (10975537).

Almost surely, 2^21951073 is an apocalyptic number.

It is an amenable number.

21951073 is a deficient number, since it is larger than the sum of its proper divisors (1).

21951073 is an equidigital number, since it uses as much as digits as its factorization.

21951073 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1890, while the sum is 28.

The square root of 21951073 is about 4685.1972210356. The cubic root of 21951073 is about 279.9960586180.

Adding to 21951073 its reverse (37015912), we get a palindrome (58966985).

The spelling of 21951073 in words is "twenty-one million, nine hundred fifty-one thousand, seventy-three".