21081147 has 16 divisors (see below), whose sum is σ = 29137920. Its totient is φ = 13543200.

The previous prime is 21081143. The next prime is 21081161. The reversal of 21081147 is 74118012.

It is not a de Polignac number, because 21081147 - 2² = 21081143 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21081143) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 38697 + ... + 39237.

It is an arithmetic number, because the mean of its divisors is an integer number (1821120).

Almost surely, 2^21081147 is an apocalyptic number.

21081147 is a deficient number, since it is larger than the sum of its proper divisors (8056773).

21081147 is a wasteful number, since it uses less digits than its factorization.

21081147 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 994.

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

The square root of 21081147 is about 4591.4210218624. The cubic root of 21081147 is about 276.2473234659.

Adding to 21081147 its reverse (74118012), we get a palindrome (95199159).

The spelling of 21081147 in words is "twenty-one million, eighty-one thousand, one hundred forty-seven".