21000021123 has 8 divisors (see below), whose sum is σ = 28004928336. Its totient is φ = 13997564000.

The previous prime is 21000021113. The next prime is 21000021127. The reversal of 21000021123 is 32112000012.

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 21000021123 - 2⁶ = 21000021059 is a prime.

It is a super-2 number, since 2×21000021123² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21000021099 and 21000021108.

It is not an unprimeable number, because it can be changed into a prime (21000021127) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 592428 + ... + 626873.

It is an arithmetic number, because the mean of its divisors is an integer number (3500616042).

Almost surely, 2^21000021123 is an apocalyptic number.

21000021123 is a deficient number, since it is larger than the sum of its proper divisors (7004907213).

21000021123 is a wasteful number, since it uses less digits than its factorization.

21000021123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1225045.

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

Adding to 21000021123 its reverse (32112000012), we get a palindrome (53112021135).

The spelling of 21000021123 in words is "twenty-one billion, twenty-one thousand, one hundred twenty-three".