21000023121 has 32 divisors (see below), whose sum is σ = 35254803456. Its totient is φ = 10801080000.

The previous prime is 21000023119. The next prime is 21000023129. The reversal of 21000023121 is 12132000012.

It is not a de Polignac number, because 21000023121 - 2¹ = 21000023119 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21000023097 and 21000023106.

It is not an unprimeable number, because it can be changed into a prime (21000023129) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 426715 + ... + 473376.

It is an arithmetic number, because the mean of its divisors is an integer number (1101712608).

Almost surely, 2^21000023121 is an apocalyptic number.

21000023121 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21000023121 is a deficient number, since it is larger than the sum of its proper divisors (14254780335).

21000023121 is a wasteful number, since it uses less digits than its factorization.

21000023121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 900213.

The product of its (nonzero) digits is 24, while the sum is 12.

Adding to 21000023121 its reverse (12132000012), we get a palindrome (33132023133).

The spelling of 21000023121 in words is "twenty-one billion, twenty-three thousand, one hundred twenty-one".