21121310320155 has 24 divisors (see below), whose sum is σ = 37210439607120. Its totient is φ = 11080031641920.

The previous prime is 21121310320133. The next prime is 21121310320217. The reversal of 21121310320155 is 55102301312112.

21121310320155 is a `hidden beast` number, since 2 + 1 + 1 + 21 + 310 + 320 + 1 + 5 + 5 = 666.

It is not a de Polignac number, because 21121310320155 - 2¹⁵ = 21121310287387 is a prime.

It is a super-2 number, since 2×21121310320155² (a number of 27 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3847230465 + ... + 3847235954.

It is an arithmetic number, because the mean of its divisors is an integer number (1550434983630).

Almost surely, 2^{21121310320155} is an apocalyptic number.

21121310320155 is a deficient number, since it is larger than the sum of its proper divisors (16089129286965).

21121310320155 is a wasteful number, since it uses less digits than its factorization.

21121310320155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7694466491 (or 7694466488 counting only the distinct ones).

The product of its (nonzero) digits is 1800, while the sum is 27.

Adding to 21121310320155 its reverse (55102301312112), we get a palindrome (76223611632267).

The spelling of 21121310320155 in words is "twenty-one trillion, one hundred twenty-one billion, three hundred ten million, three hundred twenty thousand, one hundred fifty-five".