21571841 has 2 divisors, whose sum is σ = 21571842. Its totient is φ = 21571840.

The previous prime is 21571831. The next prime is 21571867. The reversal of 21571841 is 14817512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11937025 + 9634816 = 3455^2 + 3104^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21571841 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21571801) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10785920 + 10785921.

It is an arithmetic number, because the mean of its divisors is an integer number (10785921).

Almost surely, 2^21571841 is an apocalyptic number.

It is an amenable number.

21571841 is a deficient number, since it is larger than the sum of its proper divisors (1).

21571841 is an equidigital number, since it uses as much as digits as its factorization.

21571841 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2240, while the sum is 29.

The square root of 21571841 is about 4644.5496014145. The cubic root of 21571841 is about 278.3742565554.

The spelling of 21571841 in words is "twenty-one million, five hundred seventy-one thousand, eight hundred forty-one".