21090969 has 16 divisors (see below), whose sum is σ = 32891200. Its totient is φ = 13320288.

The previous prime is 21090967. The next prime is 21091003. The reversal of 21090969 is 96909012.

It is not a de Polignac number, because 21090969 - 2¹ = 21090967 is a prime.

It is a super-2 number, since 2×21090969² = 889657946717922, which contains 22 as substring.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21090967) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 20044 + ... + 21069.

It is an arithmetic number, because the mean of its divisors is an integer number (2055700).

Almost surely, 2^21090969 is an apocalyptic number.

It is an amenable number.

21090969 is a deficient number, since it is larger than the sum of its proper divisors (11800231).

21090969 is a wasteful number, since it uses less digits than its factorization.

21090969 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41141 (or 41135 counting only the distinct ones).

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

The square root of 21090969 is about 4592.4905008067. The cubic root of 21090969 is about 276.2902192965.

The spelling of 21090969 in words is "twenty-one million, ninety thousand, nine hundred sixty-nine".