1978290861 has 8 divisors (see below), whose sum is σ = 2647109184. Its totient is φ = 1314166560.

The previous prime is 1978290859. The next prime is 1978290869. The reversal of 1978290861 is 1680928791.

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

It is not a de Polignac number, because 1978290861 - 2¹ = 1978290859 is a prime.

It is a super-2 number, since 2×1978290861² = 7827269461432242642, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1978290869) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1172521 + ... + 1174206.

It is an arithmetic number, because the mean of its divisors is an integer number (330888648).

Almost surely, 2^1978290861 is an apocalyptic number.

It is an amenable number.

1978290861 is a deficient number, since it is larger than the sum of its proper divisors (668818323).

1978290861 is a wasteful number, since it uses less digits than its factorization.

1978290861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2347011.

The product of its (nonzero) digits is 435456, while the sum is 51.

The square root of 1978290861 is about 44477.9817550212. The cubic root of 1978290861 is about 1255.3458221703.

The spelling of 1978290861 in words is "one billion, nine hundred seventy-eight million, two hundred ninety thousand, eight hundred sixty-one".