21355956009 has 12 divisors (see below), whose sum is σ = 31152914052. Its totient is φ = 14096340000.

The previous prime is 21355956001. The next prime is 21355956029. The reversal of 21355956009 is 90065955312.

21355956009 is a `hidden beast` number, since 2 + 1 + 35 + 5 + 9 + 5 + 600 + 9 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 19476993600 + 1878962409 = 139560^2 + 43347^2 .

It is not a de Polignac number, because 21355956009 - 2³ = 21355956001 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21355956001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 11746042 + ... + 11747859.

It is an arithmetic number, because the mean of its divisors is an integer number (2596076171).

Almost surely, 2^21355956009 is an apocalyptic number.

It is an amenable number.

21355956009 is a deficient number, since it is larger than the sum of its proper divisors (9796958043).

21355956009 is a wasteful number, since it uses less digits than its factorization.

21355956009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23494008 (or 23494005 counting only the distinct ones).

The product of its (nonzero) digits is 364500, while the sum is 45.

The spelling of 21355956009 in words is "twenty-one billion, three hundred fifty-five million, nine hundred fifty-six thousand, nine".