21938473 has 2 divisors, whose sum is σ = 21938474. Its totient is φ = 21938472.

The previous prime is 21938459. The next prime is 21938479. The reversal of 21938473 is 37483912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21827584 + 110889 = 4672^2 + 333^2 .

It is a cyclic number.

It is not a de Polignac number, because 21938473 - 2¹³ = 21930281 is a prime.

It is not a weakly prime, because it can be changed into another prime (21938479) 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, 10969236 + 10969237.

It is an arithmetic number, because the mean of its divisors is an integer number (10969237).

Almost surely, 2^21938473 is an apocalyptic number.

It is an amenable number.

21938473 is a deficient number, since it is larger than the sum of its proper divisors (1).

21938473 is an equidigital number, since it uses as much as digits as its factorization.

21938473 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 36288, while the sum is 37.

The square root of 21938473 is about 4683.8523674429. The cubic root of 21938473 is about 279.9424754276.

The spelling of 21938473 in words is "twenty-one million, nine hundred thirty-eight thousand, four hundred seventy-three".