21054521 has 2 divisors, whose sum is σ = 21054522. Its totient is φ = 21054520.

The previous prime is 21054457. The next prime is 21054533. The reversal of 21054521 is 12545012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20839225 + 215296 = 4565^2 + 464^2 .

It is a cyclic number.

It is not a de Polignac number, because 21054521 - 2⁶ = 21054457 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is an alternating number because its digits alternate between even and odd.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21054493 and 21054502.

It is not a weakly prime, because it can be changed into another prime (21054541) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10527260 + 10527261.

It is an arithmetic number, because the mean of its divisors is an integer number (10527261).

Almost surely, 2^21054521 is an apocalyptic number.

It is an amenable number.

21054521 is a deficient number, since it is larger than the sum of its proper divisors (1).

21054521 is an equidigital number, since it uses as much as digits as its factorization.

21054521 is an odious number, because the sum of its binary digits is odd.

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

The square root of 21054521 is about 4588.5205676776. The cubic root of 21054521 is about 276.1309721106.

Adding to 21054521 its reverse (12545012), we get a palindrome (33599533).

The spelling of 21054521 in words is "twenty-one million, fifty-four thousand, five hundred twenty-one".