21228785 has 8 divisors (see below), whose sum is σ = 25570176. Its totient is φ = 16919280.

The previous prime is 21228773. The next prime is 21228791. The reversal of 21228785 is 58782212.

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

It is not a de Polignac number, because 21228785 - 2¹² = 21224689 is a prime.

It is a super-2 number, since 2×21228785² = 901322625152450, which contains 22 as substring.

It is a Duffinian number.

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, 6479 + ... + 9188.

It is an arithmetic number, because the mean of its divisors is an integer number (3196272).

Almost surely, 2^21228785 is an apocalyptic number.

It is an amenable number.

21228785 is a deficient number, since it is larger than the sum of its proper divisors (4341391).

21228785 is a wasteful number, since it uses less digits than its factorization.

21228785 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15943.

The product of its digits is 17920, while the sum is 35.

The square root of 21228785 is about 4607.4705642033. The cubic root of 21228785 is about 276.8907065776.

The spelling of 21228785 in words is "twenty-one million, two hundred twenty-eight thousand, seven hundred eighty-five".