21290147 has 4 divisors (see below), whose sum is σ = 22024320. Its totient is φ = 20555976.

The previous prime is 21290141. The next prime is 21290161. The reversal of 21290147 is 74109212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21290147 - 2⁶ = 21290083 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21290141) 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, 367043 + ... + 367100.

It is an arithmetic number, because the mean of its divisors is an integer number (5506080).

Almost surely, 2^21290147 is an apocalyptic number.

21290147 is a deficient number, since it is larger than the sum of its proper divisors (734173).

21290147 is an equidigital number, since it uses as much as digits as its factorization.

21290147 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 734172.

The product of its (nonzero) digits is 1008, while the sum is 26.

The square root of 21290147 is about 4614.1247273996. The cubic root of 21290147 is about 277.1572349934.

Adding to 21290147 its reverse (74109212), we get a palindrome (95399359).

The spelling of 21290147 in words is "twenty-one million, two hundred ninety thousand, one hundred forty-seven".