21155108867 has 4 divisors (see below), whose sum is σ = 21159414480. Its totient is φ = 21150803256.

The previous prime is 21155108837. The next prime is 21155108899. The reversal of 21155108867 is 76880155112.

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 21155108867 - 2¹² = 21155104771 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21155108837) 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, 2145428 + ... + 2155265.

It is an arithmetic number, because the mean of its divisors is an integer number (5289853620).

Almost surely, 2^21155108867 is an apocalyptic number.

21155108867 is a deficient number, since it is larger than the sum of its proper divisors (4305613).

21155108867 is an equidigital number, since it uses as much as digits as its factorization.

21155108867 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4305612.

The product of its (nonzero) digits is 134400, while the sum is 44.

The spelling of 21155108867 in words is "twenty-one billion, one hundred fifty-five million, one hundred eight thousand, eight hundred sixty-seven".