21864719 has 4 divisors (see below), whose sum is σ = 22110480. Its totient is φ = 21618960.

The previous prime is 21864659. The next prime is 21864757. The reversal of 21864719 is 91746812.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21864719 is a prime.

It is a super-2 number, since 2×21864719² = 956131873897922, 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 (21864019) 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, 122747 + ... + 122924.

It is an arithmetic number, because the mean of its divisors is an integer number (5527620).

Almost surely, 2^21864719 is an apocalyptic number.

21864719 is a deficient number, since it is larger than the sum of its proper divisors (245761).

21864719 is an equidigital number, since it uses as much as digits as its factorization.

21864719 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 245760.

The product of its digits is 24192, while the sum is 38.

The square root of 21864719 is about 4675.9725191665. The cubic root of 21864719 is about 279.6284144030.

The spelling of 21864719 in words is "twenty-one million, eight hundred sixty-four thousand, seven hundred nineteen".