9861921801 has 20 divisors (see below), whose sum is σ = 15240010500. Its totient is φ = 6347902176.

The previous prime is 9861921793. The next prime is 9861921827. The reversal of 9861921801 is 1081291689.

9861921801 is a `hidden beast` number, since 9 + 8 + 619 + 21 + 8 + 0 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 7126736400 + 2735185401 = 84420^2 + 52299^2 .

It is not a de Polignac number, because 9861921801 - 2³ = 9861921793 is a prime.

It is not an unprimeable number, because it can be changed into a prime (9861921001) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 2096826 + ... + 2101523.

It is an arithmetic number, because the mean of its divisors is an integer number (762000525).

Almost surely, 2^9861921801 is an apocalyptic number.

It is an amenable number.

9861921801 is a deficient number, since it is larger than the sum of its proper divisors (5378088699).

9861921801 is a wasteful number, since it uses less digits than its factorization.

9861921801 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4198390 (or 4198381 counting only the distinct ones).

The product of its (nonzero) digits is 62208, while the sum is 45.

The square root of 9861921801 is about 99307.2092096037. The cubic root of 9861921801 is about 2144.4726817612.

The spelling of 9861921801 in words is "nine billion, eight hundred sixty-one million, nine hundred twenty-one thousand, eight hundred one".