21007282123 has 4 divisors (see below), whose sum is σ = 21303159408. Its totient is φ = 20711404840.

The previous prime is 21007282099. The next prime is 21007282129. The reversal of 21007282123 is 32128270012.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21007282123 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21007282091 and 21007282100.

It is not an unprimeable number, because it can be changed into a prime (21007282129) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 147938536 + ... + 147938677.

It is an arithmetic number, because the mean of its divisors is an integer number (5325789852).

Almost surely, 2^21007282123 is an apocalyptic number.

21007282123 is a deficient number, since it is larger than the sum of its proper divisors (295877285).

21007282123 is an equidigital number, since it uses as much as digits as its factorization.

21007282123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 295877284.

The product of its (nonzero) digits is 2688, while the sum is 28.

The spelling of 21007282123 in words is "twenty-one billion, seven million, two hundred eighty-two thousand, one hundred twenty-three".