21980309 has 12 divisors (see below), whose sum is σ = 24103296. Its totient is φ = 20032272.

The previous prime is 21980293. The next prime is 21980317. The reversal of 21980309 is 90308912.

It is not a de Polignac number, because 21980309 - 2⁴ = 21980293 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21980339) 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 11 ways as a sum of consecutive naturals, for example, 13244 + ... + 14810.

It is an arithmetic number, because the mean of its divisors is an integer number (2008608).

Almost surely, 2^21980309 is an apocalyptic number.

It is an amenable number.

21980309 is a deficient number, since it is larger than the sum of its proper divisors (2122987).

21980309 is a wasteful number, since it uses less digits than its factorization.

21980309 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1676 (or 1663 counting only the distinct ones).

The product of its (nonzero) digits is 3888, while the sum is 32.

The square root of 21980309 is about 4688.3162222700. The cubic root of 21980309 is about 280.1203096928.

The spelling of 21980309 in words is "twenty-one million, nine hundred eighty thousand, three hundred nine".