20521541 has 4 divisors (see below), whose sum is σ = 20802732. Its totient is φ = 20240352.

The previous prime is 20521519. The next prime is 20521561. The reversal of 20521541 is 14512502.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 14512502 = 2 ⋅7256251.

It can be written as a sum of positive squares in 2 ways, for example, as 4950625 + 15570916 = 2225^2 + 3946^2 .

It is a cyclic number.

It is not a de Polignac number, because 20521541 - 2¹⁰ = 20520517 is a prime.

It is a super-2 number, since 2×20521541² = 842267290029362, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20521561) 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, 140486 + ... + 140631.

It is an arithmetic number, because the mean of its divisors is an integer number (5200683).

Almost surely, 2^20521541 is an apocalyptic number.

It is an amenable number.

20521541 is a deficient number, since it is larger than the sum of its proper divisors (281191).

20521541 is an equidigital number, since it uses as much as digits as its factorization.

20521541 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 281190.

The product of its (nonzero) digits is 400, while the sum is 20.

The square root of 20521541 is about 4530.0707499994. The cubic root of 20521541 is about 273.7810112002.

The spelling of 20521541 in words is "twenty million, five hundred twenty-one thousand, five hundred forty-one".