1021989661 has 16 divisors (see below), whose sum is σ = 1279479168. Its totient is φ = 793036800.

The previous prime is 1021989649. The next prime is 1021989677. The reversal of 1021989661 is 1669891201.

It is a cyclic number.

It is not a de Polignac number, because 1021989661 - 2⁷ = 1021989533 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1021989601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8980 + ... + 46093.

It is an arithmetic number, because the mean of its divisors is an integer number (79967448).

Almost surely, 2^1021989661 is an apocalyptic number.

1021989661 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1021989661 is a deficient number, since it is larger than the sum of its proper divisors (257489507).

1021989661 is a wasteful number, since it uses less digits than its factorization.

1021989661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55332.

The product of its (nonzero) digits is 46656, while the sum is 43.

The square root of 1021989661 is about 31968.5730210155. The cubic root of 1021989661 is about 1007.2768066448.

The spelling of 1021989661 in words is "one billion, twenty-one million, nine hundred eighty-nine thousand, six hundred sixty-one".