21510733 has 2 divisors, whose sum is σ = 21510734. Its totient is φ = 21510732.

The previous prime is 21510719. The next prime is 21510743. The reversal of 21510733 is 33701512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18992164 + 2518569 = 4358^2 + 1587^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21510733 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21510703) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10755366 + 10755367.

It is an arithmetic number, because the mean of its divisors is an integer number (10755367).

Almost surely, 2^21510733 is an apocalyptic number.

It is an amenable number.

21510733 is a deficient number, since it is larger than the sum of its proper divisors (1).

21510733 is an equidigital number, since it uses as much as digits as its factorization.

21510733 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 630, while the sum is 22.

The square root of 21510733 is about 4637.9664724963. The cubic root of 21510733 is about 278.1111514882. Note that the first 4 decimals are identical.

The spelling of 21510733 in words is "twenty-one million, five hundred ten thousand, seven hundred thirty-three".