21479945 has 8 divisors (see below), whose sum is σ = 25806600. Its totient is φ = 17163520.

The previous prime is 21479917. The next prime is 21479957. The reversal of 21479945 is 54997412.

It can be written as a sum of positive squares in 4 ways, for example, as 1507984 + 19971961 = 1228^2 + 4469^2 .

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

It is not a de Polignac number, because 21479945 - 2⁶ = 21479881 is a prime.

It is a super-2 number, since 2×21479945² = 922776074406050, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3281 + ... + 7329.

It is an arithmetic number, because the mean of its divisors is an integer number (3225825).

Almost surely, 2^21479945 is an apocalyptic number.

It is an amenable number.

21479945 is a deficient number, since it is larger than the sum of its proper divisors (4326655).

21479945 is a wasteful number, since it uses less digits than its factorization.

21479945 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5115.

The product of its digits is 90720, while the sum is 41.

The square root of 21479945 is about 4634.6461569358. The cubic root of 21479945 is about 277.9784026491.

The spelling of 21479945 in words is "twenty-one million, four hundred seventy-nine thousand, nine hundred forty-five".