21156772810 has 16 divisors (see below), whose sum is σ = 39395370600. Its totient is φ = 8170891456.

The previous prime is 21156772807. The next prime is 21156772831. The reversal of 21156772810 is 1827765112.

It can be written as a sum of positive squares in 4 ways, for example, as 15900957801 + 5255815009 = 126099^2 + 72497^2 .

It is a super-2 number, since 2×21156772810² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 36476905 + ... + 36477484.

Almost surely, 2^21156772810 is an apocalyptic number.

21156772810 is a deficient number, since it is larger than the sum of its proper divisors (18238597790).

21156772810 is a wasteful number, since it uses less digits than its factorization.

21156772810 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72954425.

The product of its (nonzero) digits is 47040, while the sum is 40.

The spelling of 21156772810 in words is "twenty-one billion, one hundred fifty-six million, seven hundred seventy-two thousand, eight hundred ten".