21259138628 has 48 divisors (see below), whose sum is σ = 46723420800. Its totient is φ = 8410201632.

The previous prime is 21259138543. The next prime is 21259138633. The reversal of 21259138628 is 82683195212.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 578126 + ... + 613797.

It is an arithmetic number, because the mean of its divisors is an integer number (973404600).

Almost surely, 2^21259138628 is an apocalyptic number.

21259138628 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21259138628 is an abundant number, since it is smaller than the sum of its proper divisors (25464282172).

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

21259138628 is a wasteful number, since it uses less digits than its factorization.

21259138628 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1191961 (or 1191945 counting only the distinct ones).

The product of its digits is 414720, while the sum is 47.

The spelling of 21259138628 in words is "twenty-one billion, two hundred fifty-nine million, one hundred thirty-eight thousand, six hundred twenty-eight".