21521065 has 16 divisors (see below), whose sum is σ = 27931392. Its totient is φ = 15856384.

The previous prime is 21521051. The next prime is 21521083. The reversal of 21521065 is 56012512.

It is a cyclic number.

It is not a de Polignac number, because 21521065 - 2⁵ = 21521033 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1302 + ... + 6688.

It is an arithmetic number, because the mean of its divisors is an integer number (1745712).

Almost surely, 2^21521065 is an apocalyptic number.

It is an amenable number.

21521065 is a deficient number, since it is larger than the sum of its proper divisors (6410327).

21521065 is a wasteful number, since it uses less digits than its factorization.

21521065 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5456.

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

The square root of 21521065 is about 4639.0801890030. The cubic root of 21521065 is about 278.1556716584.

Adding to 21521065 its reverse (56012512), we get a palindrome (77533577).

The spelling of 21521065 in words is "twenty-one million, five hundred twenty-one thousand, sixty-five".