21021403123 has 12 divisors (see below), whose sum is σ = 24455891952. Its totient is φ = 18016560240.

The previous prime is 21021403121. The next prime is 21021403129. The reversal of 21021403123 is 32130412012.

It is a happy number.

It is not a de Polignac number, because 21021403123 - 2¹ = 21021403121 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 21021403123.

It is not an unprimeable number, because it can be changed into a prime (21021403121) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 794853 + ... + 820873.

It is an arithmetic number, because the mean of its divisors is an integer number (2037990996).

Almost surely, 2^21021403123 is an apocalyptic number.

21021403123 is a deficient number, since it is larger than the sum of its proper divisors (3434488829).

21021403123 is a wasteful number, since it uses less digits than its factorization.

21021403123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42522 (or 42515 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 19.

Adding to 21021403123 its reverse (32130412012), we get a palindrome (53151815135).

The spelling of 21021403123 in words is "twenty-one billion, twenty-one million, four hundred three thousand, one hundred twenty-three".