21801147 has 4 divisors (see below), whose sum is σ = 29068200. Its totient is φ = 14534096.

The previous prime is 21801133. The next prime is 21801161. The reversal of 21801147 is 74110812.

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

It is an interprime number because it is at equal distance from previous prime (21801133) and next prime (21801161).

It is a cyclic number.

It is not a de Polignac number, because 21801147 - 2⁷ = 21801019 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21801187) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 3633522 + ... + 3633527.

It is an arithmetic number, because the mean of its divisors is an integer number (7267050).

Almost surely, 2^21801147 is an apocalyptic number.

21801147 is a deficient number, since it is larger than the sum of its proper divisors (7267053).

21801147 is an equidigital number, since it uses as much as digits as its factorization.

21801147 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7267052.

The product of its (nonzero) digits is 448, while the sum is 24.

The square root of 21801147 is about 4669.1698405605. The cubic root of 21801147 is about 279.3571433817.

Adding to 21801147 its reverse (74110812), we get a palindrome (95911959).

The spelling of 21801147 in words is "twenty-one million, eight hundred one thousand, one hundred forty-seven".