21499819 has 8 divisors (see below), whose sum is σ = 23718960. Its totient is φ = 19324800.

The previous prime is 21499813. The next prime is 21499823. The reversal of 21499819 is 91899412.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21499819 - 2⁵ = 21499787 is a prime.

It is a super-2 number, since 2×21499819² = 924484434065522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21499813) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10002 + ... + 11959.

It is an arithmetic number, because the mean of its divisors is an integer number (2964870).

Almost surely, 2^21499819 is an apocalyptic number.

21499819 is a deficient number, since it is larger than the sum of its proper divisors (2219141).

21499819 is a wasteful number, since it uses less digits than its factorization.

21499819 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22061.

The product of its digits is 46656, while the sum is 43.

The square root of 21499819 is about 4636.7897299748. The cubic root of 21499819 is about 278.0641080178.

The spelling of 21499819 in words is "twenty-one million, four hundred ninety-nine thousand, eight hundred nineteen".