21769691 has 4 divisors (see below), whose sum is σ = 22520400. Its totient is φ = 21018984.

The previous prime is 21769681. The next prime is 21769717. The reversal of 21769691 is 19696712.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21769691 - 2¹⁰ = 21768667 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21769651) 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, 375311 + ... + 375368.

It is an arithmetic number, because the mean of its divisors is an integer number (5630100).

Almost surely, 2^21769691 is an apocalyptic number.

21769691 is a deficient number, since it is larger than the sum of its proper divisors (750709).

21769691 is an equidigital number, since it uses as much as digits as its factorization.

21769691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 750708.

The product of its digits is 40824, while the sum is 41.

The square root of 21769691 is about 4665.8001457413. The cubic root of 21769691 is about 279.2227209734. Note that the first 3 decimals are identical.

The spelling of 21769691 in words is "twenty-one million, seven hundred sixty-nine thousand, six hundred ninety-one".