978651661 has 8 divisors (see below), whose sum is σ = 1090275480. Its totient is φ = 872219712.

The previous prime is 978651659. The next prime is 978651671. The reversal of 978651661 is 166156879.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 51753636 + 926898025 = 7194^2 + 30445^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 978651661 - 2¹ = 978651659 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (978651671) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1297570 + ... + 1298323.

It is an arithmetic number, because the mean of its divisors is an integer number (136284435).

Almost surely, 2^978651661 is an apocalyptic number.

It is an amenable number.

978651661 is a deficient number, since it is larger than the sum of its proper divisors (111623819).

978651661 is a wasteful number, since it uses less digits than its factorization.

978651661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2595935.

The product of its digits is 544320, while the sum is 49.

The square root of 978651661 is about 31283.4087177213. The cubic root of 978651661 is about 992.8326386631.

The spelling of 978651661 in words is "nine hundred seventy-eight million, six hundred fifty-one thousand, six hundred sixty-one".