21123012629 has 4 divisors (see below), whose sum is σ = 21123591180. Its totient is φ = 21122434080.

The previous prime is 21123012623. The next prime is 21123012637. The reversal of 21123012629 is 92621032112.

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

It can be written as a sum of positive squares in 2 ways, for example, as 10408692529 + 10714320100 = 102023^2 + 103510^2 .

It is a cyclic number.

It is not a de Polignac number, because 21123012629 - 2¹⁶ = 21122947093 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21123012623) 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, 230534 + ... + 308855.

It is an arithmetic number, because the mean of its divisors is an integer number (5280897795).

Almost surely, 2^21123012629 is an apocalyptic number.

It is an amenable number.

21123012629 is a deficient number, since it is larger than the sum of its proper divisors (578551).

21123012629 is an equidigital number, since it uses as much as digits as its factorization.

21123012629 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 578550.

The product of its (nonzero) digits is 2592, while the sum is 29.

The spelling of 21123012629 in words is "twenty-one billion, one hundred twenty-three million, twelve thousand, six hundred twenty-nine".