21113919 has 8 divisors (see below), whose sum is σ = 31279920. Its totient is φ = 14075928.

The previous prime is 21113887. The next prime is 21113927. The reversal of 21113919 is 91931112.

It is not a de Polignac number, because 21113919 - 2⁵ = 21113887 is a prime.

It is a super-2 number, since 2×21113919² = 891595151077122, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27), and also a Moran number because the ratio is a prime number: 781997 = 21113919 / (2 + 1 + 1 + 1 + 3 + 9 + 1 + 9).

It is a junction number, because it is equal to n+sod(n) for n = 21113892 and 21113901.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21113999) 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, 390972 + ... + 391025.

It is an arithmetic number, because the mean of its divisors is an integer number (3909990).

Almost surely, 2^21113919 is an apocalyptic number.

21113919 is a deficient number, since it is larger than the sum of its proper divisors (10166001).

21113919 is an equidigital number, since it uses as much as digits as its factorization.

21113919 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 782006 (or 782000 counting only the distinct ones).

The product of its digits is 486, while the sum is 27.

The square root of 21113919 is about 4594.9884657091. The cubic root of 21113919 is about 276.3903974344.

The spelling of 21113919 in words is "twenty-one million, one hundred thirteen thousand, nine hundred nineteen".