21123015726 has 16 divisors (see below), whose sum is σ = 42278821200. Its totient is φ = 7035540288.

The previous prime is 21123015721. The next prime is 21123015743. The reversal of 21123015726 is 62751032112.

It is a junction number, because it is equal to n+sod(n) for n = 21123015693 and 21123015702.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21123015721) 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, 1357861 + ... + 1373328.

It is an arithmetic number, because the mean of its divisors is an integer number (2642426325).

Almost surely, 2^21123015726 is an apocalyptic number.

21123015726 is an abundant number, since it is smaller than the sum of its proper divisors (21155805474).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21123015726 is a wasteful number, since it uses less digits than its factorization.

21123015726 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2732483.

The product of its (nonzero) digits is 5040, while the sum is 30.

Adding to 21123015726 its reverse (62751032112), we get a palindrome (83874047838).

The spelling of 21123015726 in words is "twenty-one billion, one hundred twenty-three million, fifteen thousand, seven hundred twenty-six".