8501221981 has 16 divisors (see below), whose sum is σ = 10150790400. Its totient is φ = 6961223808.

The previous prime is 8501221901. The next prime is 8501221997. The reversal of 8501221981 is 1891221058.

It is not a de Polignac number, because 8501221981 - 2¹¹ = 8501219933 is a prime.

It is a super-2 number, since 2×8501221981² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 8501221981.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8501221901) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 97615 + ... + 162883.

It is an arithmetic number, because the mean of its divisors is an integer number (634424400).

Almost surely, 2^8501221981 is an apocalyptic number.

It is an amenable number.

8501221981 is a deficient number, since it is larger than the sum of its proper divisors (1649568419).

8501221981 is a wasteful number, since it uses less digits than its factorization.

8501221981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66108.

The product of its (nonzero) digits is 11520, while the sum is 37.

The square root of 8501221981 is about 92202.0714572075. The cubic root of 8501221981 is about 2040.9253444094.

The spelling of 8501221981 in words is "eight billion, five hundred one million, two hundred twenty-one thousand, nine hundred eighty-one".