21057634505 has 8 divisors (see below), whose sum is σ = 25313574600. Its totient is φ = 16816498816.

The previous prime is 21057634501. The next prime is 21057634529. The reversal of 21057634505 is 50543675012.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 31764496 + 21025870009 = 5636^2 + 145003^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21057634505 - 2² = 21057634501 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21057634501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3697970 + ... + 3703659.

It is an arithmetic number, because the mean of its divisors is an integer number (3164196825).

Almost surely, 2^21057634505 is an apocalyptic number.

It is an amenable number.

21057634505 is a deficient number, since it is larger than the sum of its proper divisors (4255940095).

21057634505 is an equidigital number, since it uses as much as digits as its factorization.

21057634505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7402203.

The product of its (nonzero) digits is 126000, while the sum is 38.

The spelling of 21057634505 in words is "twenty-one billion, fifty-seven million, six hundred thirty-four thousand, five hundred five".