21042696906 has 324 divisors, whose sum is σ = 60702931926. Its totient is φ = 5245067520.

The previous prime is 21042696893. The next prime is 21042696919. The reversal of 21042696906 is 60969624012.

21042696906 is a `hidden beast` number, since 210 + 426 + 9 + 6 + 9 + 0 + 6 = 666.

It is an interprime number because it is at equal distance from previous prime (21042696893) and next prime (21042696919).

It can be written as a sum of positive squares in 3 ways, for example, as 20844140625 + 198556281 = 144375^2 + 14091^2 .

It is an unprimeable number.

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 161 ways as a sum of consecutive naturals, for example, 288256086 + ... + 288256158.

Almost surely, 2^21042696906 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21042696906, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30351465963).

21042696906 is an abundant number, since it is smaller than the sum of its proper divisors (39660235020).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21042696906 is a wasteful number, since it uses less digits than its factorization.

21042696906 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 227 (or 133 counting only the distinct ones).

The product of its (nonzero) digits is 279936, while the sum is 45.

The spelling of 21042696906 in words is "twenty-one billion, forty-two million, six hundred ninety-six thousand, nine hundred six".