21155100215 has 8 divisors (see below), whose sum is σ = 25389782208. Its totient is φ = 16921638880.

The previous prime is 21155100209. The next prime is 21155100223. The reversal of 21155100215 is 51200155112.

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

It is not a de Polignac number, because 21155100215 - 2¹² = 21155096119 is a prime.

It is a Duffinian number.

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, 266591 + ... + 336720.

It is an arithmetic number, because the mean of its divisors is an integer number (3173722776).

Almost surely, 2^21155100215 is an apocalyptic number.

21155100215 is a deficient number, since it is larger than the sum of its proper divisors (4234681993).

21155100215 is an equidigital number, since it uses as much as digits as its factorization.

21155100215 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 610329.

The product of its (nonzero) digits is 500, while the sum is 23.

Adding to 21155100215 its reverse (51200155112), we get a palindrome (72355255327).

The spelling of 21155100215 in words is "twenty-one billion, one hundred fifty-five million, one hundred thousand, two hundred fifteen".