21215521505 has 8 divisors (see below), whose sum is σ = 26798553600. Its totient is φ = 16079132016.

The previous prime is 21215521499. The next prime is 21215521529. The reversal of 21215521505 is 50512551212.

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

It is a cyclic number.

It is not a de Polignac number, because 21215521505 - 2¹² = 21215517409 is a prime.

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, 111660545 + ... + 111660734.

It is an arithmetic number, because the mean of its divisors is an integer number (3349819200).

Almost surely, 2^21215521505 is an apocalyptic number.

It is an amenable number.

21215521505 is a deficient number, since it is larger than the sum of its proper divisors (5583032095).

21215521505 is a wasteful number, since it uses less digits than its factorization.

21215521505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 223321303.

The product of its (nonzero) digits is 5000, while the sum is 29.

The spelling of 21215521505 in words is "twenty-one billion, two hundred fifteen million, five hundred twenty-one thousand, five hundred five".