21321719 has 4 divisors (see below), whose sum is σ = 21345840. Its totient is φ = 21297600.

The previous prime is 21321709. The next prime is 21321733. The reversal of 21321719 is 91712312.

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 21321719 - 2¹² = 21317623 is a prime.

It is a super-2 number, since 2×21321719² = 909231402229922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21321709) 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, 10682 + ... + 12519.

It is an arithmetic number, because the mean of its divisors is an integer number (5336460).

Almost surely, 2^21321719 is an apocalyptic number.

21321719 is a deficient number, since it is larger than the sum of its proper divisors (24121).

21321719 is an equidigital number, since it uses as much as digits as its factorization.

21321719 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24120.

The product of its digits is 756, while the sum is 26.

The square root of 21321719 is about 4617.5446938822. The cubic root of 21321719 is about 277.2941697978.

The spelling of 21321719 in words is "twenty-one million, three hundred twenty-one thousand, seven hundred nineteen".