261497978 has 16 divisors (see below), whose sum is σ = 474652224. Its totient is φ = 105478080.

The previous prime is 261497963. The next prime is 261497993. The reversal of 261497978 is 879794162.

It is an interprime number because it is at equal distance from previous prime (261497963) and next prime (261497993).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 549128 + ... + 549603.

It is an arithmetic number, because the mean of its divisors is an integer number (29665764).

Almost surely, 2^261497978 is an apocalyptic number.

261497978 is a deficient number, since it is larger than the sum of its proper divisors (213154246).

261497978 is a wasteful number, since it uses less digits than its factorization.

261497978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1098757.

The product of its digits is 1524096, while the sum is 53.

The square root of 261497978 is about 16170.8991092023. The cubic root of 261497978 is about 639.4738334891.

The spelling of 261497978 in words is "two hundred sixty-one million, four hundred ninety-seven thousand, nine hundred seventy-eight".