21340286 has 24 divisors (see below), whose sum is σ = 35466312. Its totient is φ = 9622800.

The previous prime is 21340279. The next prime is 21340289. The reversal of 21340286 is 68204312.

It is a Smith number, since the sum of its digits (26) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21340289) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 39176 + ... + 39716.

It is an arithmetic number, because the mean of its divisors is an integer number (1477763).

Almost surely, 2^21340286 is an apocalyptic number.

21340286 is a deficient number, since it is larger than the sum of its proper divisors (14126026).

21340286 is a wasteful number, since it uses less digits than its factorization.

21340286 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 728 (or 717 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 26.

The square root of 21340286 is about 4619.5547404485. The cubic root of 21340286 is about 277.3746359041.

Adding to 21340286 its reverse (68204312), we get a palindrome (89544598).

The spelling of 21340286 in words is "twenty-one million, three hundred forty thousand, two hundred eighty-six".