21578045 has 8 divisors (see below), whose sum is σ = 26496096. Its totient is φ = 16860816.

The previous prime is 21578033. The next prime is 21578093. The reversal of 21578045 is 54087512.

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

It is not a de Polignac number, because 21578045 - 2⁸ = 21577789 is a prime.

It is a super-2 number, since 2×21578045² = 931224052044050, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 49967 + ... + 50396.

It is an arithmetic number, because the mean of its divisors is an integer number (3312012).

Almost surely, 2^21578045 is an apocalyptic number.

It is an amenable number.

21578045 is a deficient number, since it is larger than the sum of its proper divisors (4918051).

21578045 is a wasteful number, since it uses less digits than its factorization.

21578045 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 100411.

The product of its (nonzero) digits is 11200, while the sum is 32.

The square root of 21578045 is about 4645.2174330165. The cubic root of 21578045 is about 278.4009405452.

The spelling of 21578045 in words is "twenty-one million, five hundred seventy-eight thousand, forty-five".