21819673 has 2 divisors, whose sum is σ = 21819674. Its totient is φ = 21819672.

The previous prime is 21819659. The next prime is 21819683. The reversal of 21819673 is 37691812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17867529 + 3952144 = 4227^2 + 1988^2 .

It is a cyclic number.

It is not a de Polignac number, because 21819673 - 2¹³ = 21811481 is a prime.

It is not a weakly prime, because it can be changed into another prime (21819643) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10909836 + 10909837.

It is an arithmetic number, because the mean of its divisors is an integer number (10909837).

Almost surely, 2^21819673 is an apocalyptic number.

It is an amenable number.

21819673 is a deficient number, since it is larger than the sum of its proper divisors (1).

21819673 is an equidigital number, since it uses as much as digits as its factorization.

21819673 is an evil number, because the sum of its binary digits is even.

The product of its digits is 18144, while the sum is 37.

The square root of 21819673 is about 4671.1532837191. The cubic root of 21819673 is about 279.4362509193.

It can be divided in two parts, 218 and 19673, that added together give a palindrome (19891).

The spelling of 21819673 in words is "twenty-one million, eight hundred nineteen thousand, six hundred seventy-three".