21530447566 has 16 divisors (see below), whose sum is σ = 32427030528. Its totient is φ = 10721467800.

The previous prime is 21530447537. The next prime is 21530447573. The reversal of 21530447566 is 66574403512.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1871211 + ... + 1882681.

It is an arithmetic number, because the mean of its divisors is an integer number (2026689408).

Almost surely, 2^21530447566 is an apocalyptic number.

21530447566 is a deficient number, since it is larger than the sum of its proper divisors (10896582962).

21530447566 is a wasteful number, since it uses less digits than its factorization.

21530447566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15207.

The product of its (nonzero) digits is 604800, while the sum is 43.

The spelling of 21530447566 in words is "twenty-one billion, five hundred thirty million, four hundred forty-seven thousand, five hundred sixty-six".