21355561004 has 12 divisors (see below), whose sum is σ = 37984891728. Its totient is φ = 10502734800.

The previous prime is 21355561001. The next prime is 21355561021. The reversal of 21355561004 is 40016555312.

It is not an unprimeable number, because it can be changed into a prime (21355561001) 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 3 ways as a sum of consecutive naturals, for example, 43761152 + ... + 43761639.

It is an arithmetic number, because the mean of its divisors is an integer number (3165407644).

Almost surely, 2^21355561004 is an apocalyptic number.

It is an amenable number.

21355561004 is a deficient number, since it is larger than the sum of its proper divisors (16629330724).

21355561004 is a wasteful number, since it uses less digits than its factorization.

21355561004 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 87522856 (or 87522854 counting only the distinct ones).

The product of its (nonzero) digits is 18000, while the sum is 32.

The spelling of 21355561004 in words is "twenty-one billion, three hundred fifty-five million, five hundred sixty-one thousand, four".