21969517 has 4 divisors (see below), whose sum is σ = 22480480. Its totient is φ = 21458556.

The previous prime is 21969511. The next prime is 21969533. The reversal of 21969517 is 71596912.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21969517 - 2¹¹ = 21967469 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21969517.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21969511) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 255417 + ... + 255502.

It is an arithmetic number, because the mean of its divisors is an integer number (5620120).

Almost surely, 2^21969517 is an apocalyptic number.

It is an amenable number.

21969517 is a deficient number, since it is larger than the sum of its proper divisors (510963).

21969517 is an equidigital number, since it uses as much as digits as its factorization.

21969517 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 510962.

The product of its digits is 34020, while the sum is 40.

The square root of 21969517 is about 4687.1651347056. The cubic root of 21969517 is about 280.0744572395.

The spelling of 21969517 in words is "twenty-one million, nine hundred sixty-nine thousand, five hundred seventeen".