21135709946 has 16 divisors (see below), whose sum is σ = 34146665448. Its totient is φ = 9753696000.

The previous prime is 21135709937. The next prime is 21135709963. The reversal of 21135709946 is 64990753112.

It can be written as a sum of positive squares in 4 ways, for example, as 9724129321 + 11411580625 = 98611^2 + 106825^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21135709946.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 173846 + ... + 269246.

Almost surely, 2^21135709946 is an apocalyptic number.

21135709946 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

21135709946 is a deficient number, since it is larger than the sum of its proper divisors (13010955502).

21135709946 is a wasteful number, since it uses less digits than its factorization.

21135709946 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 103937.

The product of its (nonzero) digits is 408240, while the sum is 47.

The spelling of 21135709946 in words is "twenty-one billion, one hundred thirty-five million, seven hundred nine thousand, nine hundred forty-six".