21890329 has 2 divisors, whose sum is σ = 21890330. Its totient is φ = 21890328.

The previous prime is 21890317. The next prime is 21890369. The reversal of 21890329 is 92309812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16000000 + 5890329 = 4000^2 + 2427^2 .

It is a cyclic number.

It is not a de Polignac number, because 21890329 - 2⁷ = 21890201 is a prime.

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

It is a junction number, because it is equal to n+sod(n) for n = 21890294 and 21890303.

It is not a weakly prime, because it can be changed into another prime (21890369) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10945164 + 10945165.

It is an arithmetic number, because the mean of its divisors is an integer number (10945165).

Almost surely, 2^21890329 is an apocalyptic number.

It is an amenable number.

21890329 is a deficient number, since it is larger than the sum of its proper divisors (1).

21890329 is an equidigital number, since it uses as much as digits as its factorization.

21890329 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7776, while the sum is 34.

The square root of 21890329 is about 4678.7101855105. The cubic root of 21890329 is about 279.7375474394.

The spelling of 21890329 in words is "twenty-one million, eight hundred ninety thousand, three hundred twenty-nine".