21838501 has 2 divisors, whose sum is σ = 21838502. Its totient is φ = 21838500.

The previous prime is 21838469. The next prime is 21838507. The reversal of 21838501 is 10583812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19793601 + 2044900 = 4449^2 + 1430^2 .

It is a cyclic number.

It is not a de Polignac number, because 21838501 - 2⁵ = 21838469 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a self number, because there is not a number n which added to its sum of digits gives 21838501.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21838507) 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, 10919250 + 10919251.

It is an arithmetic number, because the mean of its divisors is an integer number (10919251).

Almost surely, 2^21838501 is an apocalyptic number.

It is an amenable number.

21838501 is a deficient number, since it is larger than the sum of its proper divisors (1).

21838501 is an equidigital number, since it uses as much as digits as its factorization.

21838501 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1920, while the sum is 28.

The square root of 21838501 is about 4673.1681972726. The cubic root of 21838501 is about 279.5166021566.

The spelling of 21838501 in words is "twenty-one million, eight hundred thirty-eight thousand, five hundred one".