21550215506 has 8 divisors (see below), whose sum is σ = 32329775100. Its totient is φ = 10773623808.

The previous prime is 21550215497. The next prime is 21550215551. The reversal of 21550215506 is 60551205512.

It can be written as a sum of positive squares in 2 ways, for example, as 20969646481 + 580569025 = 144809^2 + 24095^2 .

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

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 723731 + ... + 752918.

Almost surely, 2^21550215506 is an apocalyptic number.

21550215506 is a deficient number, since it is larger than the sum of its proper divisors (10779559594).

21550215506 is a wasteful number, since it uses less digits than its factorization.

21550215506 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1483948.

The product of its (nonzero) digits is 15000, while the sum is 32.

The spelling of 21550215506 in words is "twenty-one billion, five hundred fifty million, two hundred fifteen thousand, five hundred six".