21011550121 has 16 divisors (see below), whose sum is σ = 22829488000. Its totient is φ = 19270234368.

The previous prime is 21011550113. The next prime is 21011550127. The reversal of 21011550121 is 12105511012.

It is a cyclic number.

It is not a de Polignac number, because 21011550121 - 2³ = 21011550113 is a prime.

It is a super-2 number, since 2×21011550121² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (19).

It is not an unprimeable number, because it can be changed into a prime (21011550127) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 64801 + ... + 214993.

It is an arithmetic number, because the mean of its divisors is an integer number (1426843000).

Almost surely, 2^21011550121 is an apocalyptic number.

It is an amenable number.

21011550121 is a deficient number, since it is larger than the sum of its proper divisors (1817937879).

21011550121 is a wasteful number, since it uses less digits than its factorization.

21011550121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 150448.

The product of its (nonzero) digits is 100, while the sum is 19.

The spelling of 21011550121 in words is "twenty-one billion, eleven million, five hundred fifty thousand, one hundred twenty-one".