21055000123 has 16 divisors (see below), whose sum is σ = 23136122880. Its totient is φ = 19071876096.

The previous prime is 21055000097. The next prime is 21055000159. The reversal of 21055000123 is 32100055012.

It is a cyclic number.

It is not a de Polignac number, because 21055000123 - 2⁹ = 21054999611 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21055000123.

It is not an unprimeable number, because it can be changed into a prime (21055000163) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 86086 + ... + 222532.

It is an arithmetic number, because the mean of its divisors is an integer number (1446007680).

Almost surely, 2^21055000123 is an apocalyptic number.

21055000123 is a deficient number, since it is larger than the sum of its proper divisors (2081122757).

21055000123 is a wasteful number, since it uses less digits than its factorization.

21055000123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 136806.

The product of its (nonzero) digits is 300, while the sum is 19.

Adding to 21055000123 its reverse (32100055012), we get a palindrome (53155055135).

The spelling of 21055000123 in words is "twenty-one billion, fifty-five million, one hundred twenty-three", and thus it is an aban number.