21250340 has 24 divisors (see below), whose sum is σ = 47251512. Its totient is φ = 8000000.

The previous prime is 21250337. The next prime is 21250351. The reversal of 21250340 is 4305212.

It can be written as a sum of positive squares in 4 ways, for example, as 12166144 + 9084196 = 3488^2 + 3014^2 .

It is a Harshad number since it is a multiple of its sum of digits (17).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 30911 + ... + 31590.

It is an arithmetic number, because the mean of its divisors is an integer number (1968813).

Almost surely, 2^21250340 is an apocalyptic number.

21250340 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21250340 is an abundant number, since it is smaller than the sum of its proper divisors (26001172).

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

21250340 is a wasteful number, since it uses less digits than its factorization.

21250340 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 62527 (or 62525 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 17.

The square root of 21250340 is about 4609.8091066768. The cubic root of 21250340 is about 276.9843900720.

Adding to 21250340 its reverse (4305212), we get a palindrome (25555552).

The spelling of 21250340 in words is "twenty-one million, two hundred fifty thousand, three hundred forty".