21520801 has 4 divisors (see below), whose sum is σ = 22456512. Its totient is φ = 20585092.

The previous prime is 21520799. The next prime is 21520831. The reversal of 21520801 is 10802512.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21520801 - 2¹ = 21520799 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21520831) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 467821 + ... + 467866.

It is an arithmetic number, because the mean of its divisors is an integer number (5614128).

Almost surely, 2^21520801 is an apocalyptic number.

It is an amenable number.

21520801 is a deficient number, since it is larger than the sum of its proper divisors (935711).

21520801 is an equidigital number, since it uses as much as digits as its factorization.

21520801 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 935710.

The product of its (nonzero) digits is 160, while the sum is 19.

The square root of 21520801 is about 4639.0517349993. The cubic root of 21520801 is about 278.1545342705.

The spelling of 21520801 in words is "twenty-one million, five hundred twenty thousand, eight hundred one".