21969306 has 20 divisors (see below), whose sum is σ = 49227882. Its totient is φ = 7323048.

The previous prime is 21969293. The next prime is 21969313. The reversal of 21969306 is 60396912.

It can be written as a sum of positive squares in only one way, i.e., 14630625 + 7338681 = 3825^2 + 2709^2 .

It is a super-2 number, since 2×21969306² = 965300812243272, which contains 22 as substring.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 67645 + ... + 67968.

Almost surely, 2^21969306 is an apocalyptic number.

21969306 is an abundant number, since it is smaller than the sum of its proper divisors (27258576).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21969306 is a wasteful number, since it uses less digits than its factorization.

21969306 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 135627 (or 135618 counting only the distinct ones).

The product of its (nonzero) digits is 17496, while the sum is 36.

The square root of 21969306 is about 4687.1426263770. The cubic root of 21969306 is about 280.0735606047.

The spelling of 21969306 in words is "twenty-one million, nine hundred sixty-nine thousand, three hundred six".