20921449 has 2 divisors, whose sum is σ = 20921450. Its totient is φ = 20921448.

The previous prime is 20921431. The next prime is 20921479. The reversal of 20921449 is 94412902.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20313049 + 608400 = 4507^2 + 780^2 .

It is a cyclic number.

It is not a de Polignac number, because 20921449 - 2⁷ = 20921321 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20921449.

It is not a weakly prime, because it can be changed into another prime (20921419) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10460724 + 10460725.

It is an arithmetic number, because the mean of its divisors is an integer number (10460725).

Almost surely, 2^20921449 is an apocalyptic number.

It is an amenable number.

20921449 is a deficient number, since it is larger than the sum of its proper divisors (1).

20921449 is an equidigital number, since it uses as much as digits as its factorization.

20921449 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5184, while the sum is 31.

The square root of 20921449 is about 4573.9970485342. The cubic root of 20921449 is about 275.5479937863.

The spelling of 20921449 in words is "twenty million, nine hundred twenty-one thousand, four hundred forty-nine".