247978561 has 2 divisors, whose sum is σ = 247978562. Its totient is φ = 247978560.

The previous prime is 247978501. The next prime is 247978567. The reversal of 247978561 is 165879742.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 138650625 + 109327936 = 11775^2 + 10456^2 .

It is a cyclic number.

It is not a de Polignac number, because 247978561 - 2¹³ = 247970369 is a prime.

It is a super-2 number, since 2×247978561² = 122986733431261442, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (247978567) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 123989280 + 123989281.

It is an arithmetic number, because the mean of its divisors is an integer number (123989281).

Almost surely, 2^247978561 is an apocalyptic number.

It is an amenable number.

247978561 is a deficient number, since it is larger than the sum of its proper divisors (1).

247978561 is an equidigital number, since it uses as much as digits as its factorization.

247978561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 846720, while the sum is 49.

The square root of 247978561 is about 15747.3350443813. The cubic root of 247978561 is about 628.2580256394.

The spelling of 247978561 in words is "two hundred forty-seven million, nine hundred seventy-eight thousand, five hundred sixty-one".