21155235011 has 4 divisors (see below), whose sum is σ = 21157529592. Its totient is φ = 21152940432.

The previous prime is 21155234957. The next prime is 21155235053. The reversal of 21155235011 is 11053255112.

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 21155235011 - 2¹⁴ = 21155218627 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21155235061) 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, 1133405 + ... + 1151918.

It is an arithmetic number, because the mean of its divisors is an integer number (5289382398).

Almost surely, 2^21155235011 is an apocalyptic number.

21155235011 is a deficient number, since it is larger than the sum of its proper divisors (2294581).

21155235011 is an equidigital number, since it uses as much as digits as its factorization.

21155235011 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2294580.

The product of its (nonzero) digits is 1500, while the sum is 26.

The spelling of 21155235011 in words is "twenty-one billion, one hundred fifty-five million, two hundred thirty-five thousand, eleven".