21969890 has 16 divisors (see below), whose sum is σ = 41627520. Its totient is φ = 8325360.

The previous prime is 21969887. The next prime is 21969911. The reversal of 21969890 is 9896912.

It is a super-2 number, since 2×21969890² = 965352133224200, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 57626 + ... + 58005.

It is an arithmetic number, because the mean of its divisors is an integer number (2601720).

Almost surely, 2^21969890 is an apocalyptic number.

21969890 is a deficient number, since it is larger than the sum of its proper divisors (19657630).

21969890 is a wasteful number, since it uses less digits than its factorization.

21969890 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 115657.

The product of its (nonzero) digits is 69984, while the sum is 44.

The square root of 21969890 is about 4687.2049240459. The cubic root of 21969890 is about 280.0760422718.

The spelling of 21969890 in words is "twenty-one million, nine hundred sixty-nine thousand, eight hundred ninety".