21520965 has 8 divisors (see below), whose sum is σ = 34433568. Its totient is φ = 11477840.

The previous prime is 21520949. The next prime is 21520999. The reversal of 21520965 is 56902512.

It is a happy number.

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

It is not a de Polignac number, because 21520965 - 2⁴ = 21520949 is a prime.

It is a Curzon number.

It is a congruent 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, 717351 + ... + 717380.

It is an arithmetic number, because the mean of its divisors is an integer number (4304196).

Almost surely, 2^21520965 is an apocalyptic number.

It is an amenable number.

21520965 is a deficient number, since it is larger than the sum of its proper divisors (12912603).

21520965 is a wasteful number, since it uses less digits than its factorization.

21520965 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1434739.

The product of its (nonzero) digits is 5400, while the sum is 30.

The square root of 21520965 is about 4639.0694109918. The cubic root of 21520965 is about 278.1552408308.

The spelling of 21520965 in words is "twenty-one million, five hundred twenty thousand, nine hundred sixty-five".