21475945 has 8 divisors (see below), whose sum is σ = 26319744. Its totient is φ = 16815024.

The previous prime is 21475939. The next prime is 21475957. The reversal of 21475945 is 54957412.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21475945 is a prime.

It is a super-2 number, since 2×21475945² = 922432427286050, which contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 45459 + ... + 45928.

It is an arithmetic number, because the mean of its divisors is an integer number (3289968).

Almost surely, 2^21475945 is an apocalyptic number.

It is an amenable number.

21475945 is a deficient number, since it is larger than the sum of its proper divisors (4843799).

21475945 is an equidigital number, since it uses as much as digits as its factorization.

21475945 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 91439.

The product of its digits is 50400, while the sum is 37.

The square root of 21475945 is about 4634.2146044395. The cubic root of 21475945 is about 277.9611465118.

The spelling of 21475945 in words is "twenty-one million, four hundred seventy-five thousand, nine hundred forty-five".