21155465215 has 4 divisors (see below), whose sum is σ = 25386558264. Its totient is φ = 16924372168.

The previous prime is 21155465183. The next prime is 21155465257. The reversal of 21155465215 is 51256455112.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21155465215 - 2⁵ = 21155465183 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 3 ways as a sum of consecutive naturals, for example, 2115546517 + ... + 2115546526.

It is an arithmetic number, because the mean of its divisors is an integer number (6346639566).

Almost surely, 2^21155465215 is an apocalyptic number.

21155465215 is a deficient number, since it is larger than the sum of its proper divisors (4231093049).

21155465215 is an equidigital number, since it uses as much as digits as its factorization.

21155465215 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4231093048.

The product of its digits is 60000, while the sum is 37.

The spelling of 21155465215 in words is "twenty-one billion, one hundred fifty-five million, four hundred sixty-five thousand, two hundred fifteen".