21021555535 has 16 divisors (see below), whose sum is σ = 25315778880. Its totient is φ = 16757378560.

The previous prime is 21021555523. The next prime is 21021555539. The reversal of 21021555535 is 53555512012.

It is a de Polignac number, because none of the positive numbers 2^k-21021555535 is a prime.

It is a super-2 number, since 2×21021555535² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21021555535.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21021555539) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2783865 + ... + 2791405.

It is an arithmetic number, because the mean of its divisors is an integer number (1582236180).

Almost surely, 2^21021555535 is an apocalyptic number.

21021555535 is a deficient number, since it is larger than the sum of its proper divisors (4294223345).

21021555535 is a wasteful number, since it uses less digits than its factorization.

21021555535 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9458.

The product of its (nonzero) digits is 37500, while the sum is 34.

The spelling of 21021555535 in words is "twenty-one billion, twenty-one million, five hundred fifty-five thousand, five hundred thirty-five".