21613919 has 8 divisors (see below), whose sum is σ = 22957200. Its totient is φ = 20278656.

The previous prime is 21613909. The next prime is 21613931. The reversal of 21613919 is 91931612.

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

It is a cyclic number.

It is not a de Polignac number, because 21613919 - 2⁸ = 21613663 is a prime.

It is a super-2 number, since 2×21613919² = 934322989077122, 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 (21613909) 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, 4112 + ... + 7754.

It is an arithmetic number, because the mean of its divisors is an integer number (2869650).

Almost surely, 2^21613919 is an apocalyptic number.

21613919 is a deficient number, since it is larger than the sum of its proper divisors (1343281).

21613919 is a wasteful number, since it uses less digits than its factorization.

21613919 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4009.

The product of its digits is 2916, while the sum is 32.

The square root of 21613919 is about 4649.0772202664. The cubic root of 21613919 is about 278.5551377969. Note that the first 3 decimals are identical.

The spelling of 21613919 in words is "twenty-one million, six hundred thirteen thousand, nine hundred nineteen".