21736819 has 4 divisors (see below), whose sum is σ = 23408896. Its totient is φ = 20064744.

The previous prime is 21736769. The next prime is 21736823. The reversal of 21736819 is 91863712.

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 21736819 - 2⁷ = 21736691 is a prime.

It is a super-2 number, since 2×21736819² = 944978600477522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21736849) 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, 836019 + ... + 836044.

It is an arithmetic number, because the mean of its divisors is an integer number (5852224).

Almost surely, 2^21736819 is an apocalyptic number.

21736819 is a deficient number, since it is larger than the sum of its proper divisors (1672077).

21736819 is a wasteful number, since it uses less digits than its factorization.

21736819 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1672076.

The product of its digits is 18144, while the sum is 37.

The square root of 21736819 is about 4662.2761608468. The cubic root of 21736819 is about 279.0821090705.

The spelling of 21736819 in words is "twenty-one million, seven hundred thirty-six thousand, eight hundred nineteen".