21831147 has 48 divisors (see below), whose sum is σ = 36665440. Its totient is φ = 12752640.

The previous prime is 21831101. The next prime is 21831181. The reversal of 21831147 is 74113812.

It is not a de Polignac number, because 21831147 - 2⁸ = 21830891 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21831147.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21831647) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 532447 + ... + 532487.

Almost surely, 2^21831147 is an apocalyptic number.

21831147 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

21831147 is a deficient number, since it is larger than the sum of its proper divisors (14834293).

21831147 is a wasteful number, since it uses less digits than its factorization.

21831147 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 141 (or 94 counting only the distinct ones).

The product of its digits is 1344, while the sum is 27.

The square root of 21831147 is about 4672.3812986528. The cubic root of 21831147 is about 279.4852233871.

Adding to 21831147 its reverse (74113812), we get a palindrome (95944959).

The spelling of 21831147 in words is "twenty-one million, eight hundred thirty-one thousand, one hundred forty-seven".