21475919 has 4 divisors (see below), whose sum is σ = 21511344. Its totient is φ = 21440496.

The previous prime is 21475907. The next prime is 21475939. The reversal of 21475919 is 91957412.

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-21475919 is a prime.

It is a super-2 number, since 2×21475919² = 922430193789122, 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 (21475939) 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, 16787 + ... + 18020.

It is an arithmetic number, because the mean of its divisors is an integer number (5377836).

Almost surely, 2^21475919 is an apocalyptic number.

21475919 is a deficient number, since it is larger than the sum of its proper divisors (35425).

21475919 is an equidigital number, since it uses as much as digits as its factorization.

21475919 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35424.

The product of its digits is 22680, while the sum is 38.

The square root of 21475919 is about 4634.2117992168. The cubic root of 21475919 is about 277.9610343399.

The spelling of 21475919 in words is "twenty-one million, four hundred seventy-five thousand, nine hundred nineteen".