278590661 has 2 divisors, whose sum is σ = 278590662. Its totient is φ = 278590660.

The previous prime is 278590633. The next prime is 278590709. The reversal of 278590661 is 166095872.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 163993636 + 114597025 = 12806^2 + 10705^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-278590661 is a prime.

It is a super-2 number, since 2×278590661² = 155225512792833842, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (278590601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 139295330 + 139295331.

It is an arithmetic number, because the mean of its divisors is an integer number (139295331).

Almost surely, 2^278590661 is an apocalyptic number.

It is an amenable number.

278590661 is a deficient number, since it is larger than the sum of its proper divisors (1).

278590661 is an equidigital number, since it uses as much as digits as its factorization.

278590661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 181440, while the sum is 44.

The square root of 278590661 is about 16691.0353483539. The cubic root of 278590661 is about 653.1137863997.

The spelling of 278590661 in words is "two hundred seventy-eight million, five hundred ninety thousand, six hundred sixty-one".