21512065 has 8 divisors (see below), whose sum is σ = 26065728. Its totient is φ = 17042160.

The previous prime is 21512063. The next prime is 21512093. The reversal of 21512065 is 56021512.

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

It is not a de Polignac number, because 21512065 - 2¹ = 21512063 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21512063) 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, 20371 + ... + 21400.

It is an arithmetic number, because the mean of its divisors is an integer number (3258216).

Almost surely, 2^21512065 is an apocalyptic number.

It is an amenable number.

21512065 is a deficient number, since it is larger than the sum of its proper divisors (4553663).

21512065 is a wasteful number, since it uses less digits than its factorization.

21512065 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41879.

The product of its (nonzero) digits is 600, while the sum is 22.

The square root of 21512065 is about 4638.1100676892. The cubic root of 21512065 is about 278.1168918227.

Adding to 21512065 its reverse (56021512), we get a palindrome (77533577).

The spelling of 21512065 in words is "twenty-one million, five hundred twelve thousand, sixty-five".