21960909 has 8 divisors (see below), whose sum is σ = 32534720. Its totient is φ = 14640588.

The previous prime is 21960893. The next prime is 21960931. The reversal of 21960909 is 90906912.

It is not a de Polignac number, because 21960909 - 2⁴ = 21960893 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 (21962909) 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 7 ways as a sum of consecutive naturals, for example, 406657 + ... + 406710.

It is an arithmetic number, because the mean of its divisors is an integer number (4066840).

Almost surely, 2^21960909 is an apocalyptic number.

It is an amenable number.

21960909 is a deficient number, since it is larger than the sum of its proper divisors (10573811).

21960909 is an equidigital number, since it uses as much as digits as its factorization.

21960909 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 813376 (or 813370 counting only the distinct ones).

The product of its (nonzero) digits is 8748, while the sum is 36.

The square root of 21960909 is about 4686.2467924769. The cubic root of 21960909 is about 280.0378732783.

The spelling of 21960909 in words is "twenty-one million, nine hundred sixty thousand, nine hundred nine".