21742776155 has 4 divisors (see below), whose sum is σ = 26091331392. Its totient is φ = 17394220920.

The previous prime is 21742776137. The next prime is 21742776157. The reversal of 21742776155 is 55167724712.

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

It is not a de Polignac number, because 21742776155 - 2¹⁸ = 21742514011 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21742776157) 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, 2174277611 + ... + 2174277620.

It is an arithmetic number, because the mean of its divisors is an integer number (6522832848).

Almost surely, 2^21742776155 is an apocalyptic number.

21742776155 is a deficient number, since it is larger than the sum of its proper divisors (4348555237).

21742776155 is an equidigital number, since it uses as much as digits as its factorization.

21742776155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4348555236.

The product of its digits is 823200, while the sum is 47.

The spelling of 21742776155 in words is "twenty-one billion, seven hundred forty-two million, seven hundred seventy-six thousand, one hundred fifty-five".