21031351 has 8 divisors (see below), whose sum is σ = 23734800. Its totient is φ = 18459840.

The previous prime is 21031349. The next prime is 21031357. The reversal of 21031351 is 15313012.

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 21031351 - 2¹ = 21031349 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21031357) 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 7 ways as a sum of consecutive naturals, for example, 32646 + ... + 33283.

It is an arithmetic number, because the mean of its divisors is an integer number (2966850).

Almost surely, 2^21031351 is an apocalyptic number.

21031351 is a deficient number, since it is larger than the sum of its proper divisors (2703449).

21031351 is a wasteful number, since it uses less digits than its factorization.

21031351 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65969.

The product of its (nonzero) digits is 90, while the sum is 16.

The square root of 21031351 is about 4585.9950937610. The cubic root of 21031351 is about 276.0296430739.

Adding to 21031351 its reverse (15313012), we get a palindrome (36344363).

The spelling of 21031351 in words is "twenty-one million, thirty-one thousand, three hundred fifty-one".