21020307155 has 8 divisors (see below), whose sum is σ = 25259069472. Its totient is φ = 16793111808.

The previous prime is 21020307151. The next prime is 21020307173. The reversal of 21020307155 is 55170302012.

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

It is a cyclic number.

It is not a de Polignac number, because 21020307155 - 2² = 21020307151 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21020307151) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2887742 + ... + 2895011.

It is an arithmetic number, because the mean of its divisors is an integer number (3157383684).

Almost surely, 2^21020307155 is an apocalyptic number.

21020307155 is a deficient number, since it is larger than the sum of its proper divisors (4238762317).

21020307155 is an equidigital number, since it uses as much as digits as its factorization.

21020307155 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5783485.

The product of its (nonzero) digits is 2100, while the sum is 26.

Adding to 21020307155 its reverse (55170302012), we get a palindrome (76190609167).

The spelling of 21020307155 in words is "twenty-one billion, twenty million, three hundred seven thousand, one hundred fifty-five".