21980369 has 4 divisors (see below), whose sum is σ = 22043700. Its totient is φ = 21917040.

The previous prime is 21980363. The next prime is 21980381. The reversal of 21980369 is 96308912.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 15904144 + 6076225 = 3988^2 + 2465^2 .

It is a cyclic number.

It is not a de Polignac number, because 21980369 - 2¹⁶ = 21914833 is a prime.

It is a super-2 number, since 2×21980369² = 966273242752322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21980363) 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 in 3 ways as a sum of consecutive naturals, for example, 31142 + ... + 31839.

It is an arithmetic number, because the mean of its divisors is an integer number (5510925).

Almost surely, 2^21980369 is an apocalyptic number.

It is an amenable number.

21980369 is a deficient number, since it is larger than the sum of its proper divisors (63331).

21980369 is an equidigital number, since it uses as much as digits as its factorization.

21980369 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63330.

The product of its (nonzero) digits is 23328, while the sum is 38.

The square root of 21980369 is about 4688.3226211514. The cubic root of 21980369 is about 280.1205645755.

The spelling of 21980369 in words is "twenty-one million, nine hundred eighty thousand, three hundred sixty-nine".