21031265 has 8 divisors (see below), whose sum is σ = 25593408. Its totient is φ = 16587760.

The previous prime is 21031253. The next prime is 21031277. The reversal of 21031265 is 56213012.

It is an interprime number because it is at equal distance from previous prime (21031253) and next prime (21031277).

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

It is not a de Polignac number, because 21031265 - 2⁸ = 21031009 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 29267 + ... + 29976.

It is an arithmetic number, because the mean of its divisors is an integer number (3199176).

Almost surely, 2^21031265 is an apocalyptic number.

It is an amenable number.

21031265 is a deficient number, since it is larger than the sum of its proper divisors (4562143).

21031265 is an equidigital number, since it uses as much as digits as its factorization.

21031265 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 59319.

The product of its (nonzero) digits is 360, while the sum is 20.

The square root of 21031265 is about 4585.9857173785. The cubic root of 21031265 is about 276.0292668327.

Adding to 21031265 its reverse (56213012), we get a palindrome (77244277).

The spelling of 21031265 in words is "twenty-one million, thirty-one thousand, two hundred sixty-five".