21634533409 has 2 divisors, whose sum is σ = 21634533410. Its totient is φ = 21634533408.

The previous prime is 21634533377. The next prime is 21634533457. The reversal of 21634533409 is 90433543612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20879383009 + 755150400 = 144497^2 + 27480^2 .

It is a cyclic number.

It is not a de Polignac number, because 21634533409 - 2⁵ = 21634533377 is a prime.

It is a super-2 number, since 2×21634533409² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21634533209) 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, 10817266704 + 10817266705.

It is an arithmetic number, because the mean of its divisors is an integer number (10817266705).

Almost surely, 2^21634533409 is an apocalyptic number.

It is an amenable number.

21634533409 is a deficient number, since it is larger than the sum of its proper divisors (1).

21634533409 is an equidigital number, since it uses as much as digits as its factorization.

21634533409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 233280, while the sum is 40.

The spelling of 21634533409 in words is "twenty-one billion, six hundred thirty-four million, five hundred thirty-three thousand, four hundred nine".