21671340 has 48 divisors (see below), whose sum is σ = 60963840. Its totient is φ = 5752000.

The previous prime is 21671333. The next prime is 21671341. The reversal of 21671340 is 4317612.

It is a self number, because there is not a number n which added to its sum of digits gives 21671340.

It is not an unprimeable number, because it can be changed into a prime (21671341) 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 15 ways as a sum of consecutive naturals, for example, 14341 + ... + 15779.

It is an arithmetic number, because the mean of its divisors is an integer number (1270080).

Almost surely, 2^21671340 is an apocalyptic number.

21671340 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21671340 is an abundant number, since it is smaller than the sum of its proper divisors (39292500).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21671340 is a wasteful number, since it uses less digits than its factorization.

21671340 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1702 (or 1700 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 24.

The square root of 21671340 is about 4655.2486507167. The cubic root of 21671340 is about 278.8015958169.

Adding to 21671340 its reverse (4317612), we get a palindrome (25988952).

The spelling of 21671340 in words is "twenty-one million, six hundred seventy-one thousand, three hundred forty".