21541057 has 4 divisors (see below), whose sum is σ = 22808196. Its totient is φ = 20273920.

The previous prime is 21541049. The next prime is 21541061. The reversal of 21541057 is 75014512.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 17313921 + 4227136 = 4161^2 + 2056^2 .

It is a cyclic number.

It is not a de Polignac number, because 21541057 - 2³ = 21541049 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21541027) 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, 633544 + ... + 633577.

It is an arithmetic number, because the mean of its divisors is an integer number (5702049).

Almost surely, 2^21541057 is an apocalyptic number.

It is an amenable number.

21541057 is a deficient number, since it is larger than the sum of its proper divisors (1267139).

21541057 is a wasteful number, since it uses less digits than its factorization.

21541057 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1267138.

The product of its (nonzero) digits is 1400, while the sum is 25.

The square root of 21541057 is about 4641.2344263138. The cubic root of 21541057 is about 278.2417759342.

Adding to 21541057 its reverse (75014512), we get a palindrome (96555569).

The spelling of 21541057 in words is "twenty-one million, five hundred forty-one thousand, fifty-seven".