278871221521 has 2 divisors, whose sum is σ = 278871221522. Its totient is φ = 278871221520.

The previous prime is 278871221513. The next prime is 278871221539. The reversal of 278871221521 is 125122178872.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 162115748496 + 116755473025 = 402636^2 + 341695^2 .

It is a cyclic number.

It is not a de Polignac number, because 278871221521 - 2³ = 278871221513 is a prime.

It is a super-2 number, since 2×278871221521² (a number of 24 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (278871222521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 139435610760 + 139435610761.

It is an arithmetic number, because the mean of its divisors is an integer number (139435610761).

Almost surely, 2^278871221521 is an apocalyptic number.

It is an amenable number.

278871221521 is a deficient number, since it is larger than the sum of its proper divisors (1).

278871221521 is an equidigital number, since it uses as much as digits as its factorization.

278871221521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 250880, while the sum is 46.

The spelling of 278871221521 in words is "two hundred seventy-eight billion, eight hundred seventy-one million, two hundred twenty-one thousand, five hundred twenty-one".