21305496690 has 32 divisors (see below), whose sum is σ = 56814658560. Its totient is φ = 5681465712.

The previous prime is 21305496683. The next prime is 21305496743. The reversal of 21305496690 is 9669450312.

21305496690 is a `hidden beast` number, since 2 + 13 + 0 + 549 + 6 + 6 + 90 = 666.

It is a super-2 number, since 2×21305496690² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

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 15 ways as a sum of consecutive naturals, for example, 39454354 + ... + 39454893.

It is an arithmetic number, because the mean of its divisors is an integer number (1775458080).

Almost surely, 2^21305496690 is an apocalyptic number.

21305496690 is an abundant number, since it is smaller than the sum of its proper divisors (35509161870).

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

21305496690 is a wasteful number, since it uses less digits than its factorization.

21305496690 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 78909263 (or 78909257 counting only the distinct ones).

The product of its (nonzero) digits is 349920, while the sum is 45.

The spelling of 21305496690 in words is "twenty-one billion, three hundred five million, four hundred ninety-six thousand, six hundred ninety".