21000121123 has 8 divisors (see below), whose sum is σ = 21048923520. Its totient is φ = 20951361600.

The previous prime is 21000121111. The next prime is 21000121187. The reversal of 21000121123 is 32112100012.

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 21000121123 - 2⁹ = 21000120611 is a prime.

It is a super-2 number, since 2×21000121123² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21000121223) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1100661 + ... + 1119577.

It is an arithmetic number, because the mean of its divisors is an integer number (2631115440).

Almost surely, 2^21000121123 is an apocalyptic number.

21000121123 is a deficient number, since it is larger than the sum of its proper divisors (48802397).

21000121123 is a wasteful number, since it uses less digits than its factorization.

21000121123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21437.

The product of its (nonzero) digits is 24, while the sum is 13.

Adding to 21000121123 its reverse (32112100012), we get a palindrome (53112221135).

The spelling of 21000121123 in words is "twenty-one billion, one hundred twenty-one thousand, one hundred twenty-three".