20801521 has 8 divisors (see below), whose sum is σ = 22437800. Its totient is φ = 19170432.

The previous prime is 20801507. The next prime is 20801567. The reversal of 20801521 is 12510802.

It can be written as a sum of positive squares in 4 ways, for example, as 3370896 + 17430625 = 1836^2 + 4175^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 20801521 - 2⁷ = 20801393 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20811521) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12655 + ... + 14203.

It is an arithmetic number, because the mean of its divisors is an integer number (2804725).

Almost surely, 2^20801521 is an apocalyptic number.

It is an amenable number.

20801521 is a deficient number, since it is larger than the sum of its proper divisors (1636279).

20801521 is a wasteful number, since it uses less digits than its factorization.

20801521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2595.

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

The square root of 20801521 is about 4560.8684480042. The cubic root of 20801521 is about 275.0204767122.

The spelling of 20801521 in words is "twenty million, eight hundred one thousand, five hundred twenty-one".