21577541 has 2 divisors, whose sum is σ = 21577542. Its totient is φ = 21577540.

The previous prime is 21577511. The next prime is 21577547. The reversal of 21577541 is 14577512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13432225 + 8145316 = 3665^2 + 2854^2 .

It is a cyclic number.

It is not a de Polignac number, because 21577541 - 2⁶ = 21577477 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21577498 and 21577507.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21577547) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10788770 + 10788771.

It is an arithmetic number, because the mean of its divisors is an integer number (10788771).

Almost surely, 2^21577541 is an apocalyptic number.

It is an amenable number.

21577541 is a deficient number, since it is larger than the sum of its proper divisors (1).

21577541 is an equidigital number, since it uses as much as digits as its factorization.

21577541 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 9800, while the sum is 32.

The square root of 21577541 is about 4645.1631833553. The cubic root of 21577541 is about 278.3987729845.

The spelling of 21577541 in words is "twenty-one million, five hundred seventy-seven thousand, five hundred forty-one".