21719769 has 4 divisors (see below), whose sum is σ = 28959696. Its totient is φ = 14479844.

The previous prime is 21719767. The next prime is 21719801. The reversal of 21719769 is 96791712.

It is a happy number.

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 21719769 - 2¹ = 21719767 is a prime.

It is a super-2 number, since 2×21719769² = 943496730826722, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21719769.

It is not an unprimeable number, because it can be changed into a prime (21719767) 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, 3619959 + ... + 3619964.

It is an arithmetic number, because the mean of its divisors is an integer number (7239924).

Almost surely, 2^21719769 is an apocalyptic number.

It is an amenable number.

21719769 is a deficient number, since it is larger than the sum of its proper divisors (7239927).

21719769 is an equidigital number, since it uses as much as digits as its factorization.

21719769 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7239926.

The product of its digits is 47628, while the sum is 42.

The square root of 21719769 is about 4660.4472961294. The cubic root of 21719769 is about 279.0091208591.

The spelling of 21719769 in words is "twenty-one million, seven hundred nineteen thousand, seven hundred sixty-nine".