978493861 has 2 divisors, whose sum is σ = 978493862. Its totient is φ = 978493860.

The previous prime is 978493847. The next prime is 978493907. The reversal of 978493861 is 168394879.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 871371361 + 107122500 = 29519^2 + 10350^2 .

It is an emirp because it is prime and its reverse (168394879) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 978493861 - 2⁵ = 978493829 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (978493561) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 489246930 + 489246931.

It is an arithmetic number, because the mean of its divisors is an integer number (489246931).

Almost surely, 2^978493861 is an apocalyptic number.

It is an amenable number.

978493861 is a deficient number, since it is larger than the sum of its proper divisors (1).

978493861 is an equidigital number, since it uses as much as digits as its factorization.

978493861 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2612736, while the sum is 55.

The square root of 978493861 is about 31280.8865123737. The cubic root of 978493861 is about 992.7792736039.

The spelling of 978493861 in words is "nine hundred seventy-eight million, four hundred ninety-three thousand, eight hundred sixty-one".