21071891830 has 128 divisors (see below), whose sum is σ = 44647842816. Its totient is φ = 7082380800.

The previous prime is 21071891809. The next prime is 21071891843. The reversal of 21071891830 is 3819817012.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 15257740 + ... + 15259120.

It is an arithmetic number, because the mean of its divisors is an integer number (348811272).

Almost surely, 2^21071891830 is an apocalyptic number.

21071891830 is an abundant number, since it is smaller than the sum of its proper divisors (23575950986).

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

21071891830 is a wasteful number, since it uses less digits than its factorization.

21071891830 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1622.

The product of its (nonzero) digits is 24192, while the sum is 40.

The spelling of 21071891830 in words is "twenty-one billion, seventy-one million, eight hundred ninety-one thousand, eight hundred thirty".