21115550150521 has 4 divisors (see below), whose sum is σ = 21241990570752. Its totient is φ = 20989109730292.

The previous prime is 21115550150447. The next prime is 21115550150537. The reversal of 21115550150521 is 12505105551112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21115550150521 - 2²⁹ = 21115013279609 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21115550150921) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 63220209865 + ... + 63220210198.

It is an arithmetic number, because the mean of its divisors is an integer number (5310497642688).

Almost surely, 2^{21115550150521} is an apocalyptic number.

It is an amenable number.

21115550150521 is a deficient number, since it is larger than the sum of its proper divisors (126440420231).

21115550150521 is a wasteful number, since it uses less digits than its factorization.

21115550150521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 126440420230.

The product of its (nonzero) digits is 12500, while the sum is 34.

The spelling of 21115550150521 in words is "twenty-one trillion, one hundred fifteen billion, five hundred fifty million, one hundred fifty thousand, five hundred twenty-one".