21261339128 has 16 divisors (see below), whose sum is σ = 40237582680. Its totient is φ = 10531317088.

The previous prime is 21261339109. The next prime is 21261339137. The reversal of 21261339128 is 82193316212.

It is a junction number, because it is equal to n+sod(n) for n = 21261339091 and 21261339100.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12418151 + ... + 12419862.

Almost surely, 2^21261339128 is an apocalyptic number.

It is an amenable number.

21261339128 is a deficient number, since it is larger than the sum of its proper divisors (18976243552).

21261339128 is a wasteful number, since it uses less digits than its factorization.

21261339128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24838126 (or 24838122 counting only the distinct ones).

The product of its digits is 31104, while the sum is 38.

The spelling of 21261339128 in words is "twenty-one billion, two hundred sixty-one million, three hundred thirty-nine thousand, one hundred twenty-eight".