21729187579850 has 12 divisors (see below), whose sum is σ = 40416288898614. Its totient is φ = 8691675031920.

The previous prime is 21729187579819. The next prime is 21729187579873. The reversal of 21729187579850 is 5897578192712.

It can be written as a sum of positive squares in 3 ways, for example, as 14569405026121 + 7159782553729 = 3816989^2 + 2675777^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 217291875749 + ... + 217291875848.

Almost surely, 2^{21729187579850} is an apocalyptic number.

21729187579850 is a deficient number, since it is larger than the sum of its proper divisors (18687101318764).

21729187579850 is a wasteful number, since it uses less digits than its factorization.

21729187579850 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 434583751609 (or 434583751604 counting only the distinct ones).

The product of its (nonzero) digits is 177811200, while the sum is 71.

The spelling of 21729187579850 in words is "twenty-one trillion, seven hundred twenty-nine billion, one hundred eighty-seven million, five hundred seventy-nine thousand, eight hundred fifty".