21031345 has 8 divisors (see below), whose sum is σ = 25294464. Its totient is φ = 16787184.

The previous prime is 21031333. The next prime is 21031349. The reversal of 21031345 is 54313012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21031345 - 2⁵ = 21031313 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21031349) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2169 + ... + 6838.

It is an arithmetic number, because the mean of its divisors is an integer number (3161808).

Almost surely, 2^21031345 is an apocalyptic number.

It is an amenable number.

21031345 is a deficient number, since it is larger than the sum of its proper divisors (4263119).

21031345 is an equidigital number, since it uses as much as digits as its factorization.

21031345 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9479.

The product of its (nonzero) digits is 360, while the sum is 19.

The square root of 21031345 is about 4585.9944395954. The cubic root of 21031345 is about 276.0296168246.

Adding to 21031345 its reverse (54313012), we get a palindrome (75344357).

The spelling of 21031345 in words is "twenty-one million, thirty-one thousand, three hundred forty-five".