21987041 has 2 divisors, whose sum is σ = 21987042. Its totient is φ = 21987040.

The previous prime is 21987019. The next prime is 21987059. The reversal of 21987041 is 14078912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21715600 + 271441 = 4660^2 + 521^2 .

It is a cyclic number.

It is not a de Polignac number, because 21987041 - 2¹⁰ = 21986017 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21986989 and 21987007.

It is not a weakly prime, because it can be changed into another prime (21987071) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10993520 + 10993521.

It is an arithmetic number, because the mean of its divisors is an integer number (10993521).

Almost surely, 2^21987041 is an apocalyptic number.

It is an amenable number.

21987041 is a deficient number, since it is larger than the sum of its proper divisors (1).

21987041 is an equidigital number, since it uses as much as digits as its factorization.

21987041 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4032, while the sum is 32.

The square root of 21987041 is about 4689.0341222900. The cubic root of 21987041 is about 280.1489046417.

The spelling of 21987041 in words is "twenty-one million, nine hundred eighty-seven thousand, forty-one".