1077778721 has 2 divisors, whose sum is σ = 1077778722. Its totient is φ = 1077778720.

The previous prime is 1077778717. The next prime is 1077778739. The reversal of 1077778721 is 1278777701.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 777796321 + 299982400 = 27889^2 + 17320^2 .

It is a cyclic number.

It is not a de Polignac number, because 1077778721 - 2² = 1077778717 is a prime.

It is not a weakly prime, because it can be changed into another prime (1077178721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 538889360 + 538889361.

It is an arithmetic number, because the mean of its divisors is an integer number (538889361).

Almost surely, 2^1077778721 is an apocalyptic number.

It is an amenable number.

1077778721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1077778721 is an equidigital number, since it uses as much as digits as its factorization.

1077778721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 268912, while the sum is 47.

The square root of 1077778721 is about 32829.5403714399. The cubic root of 1077778721 is about 1025.2816900983.

It can be divided in two parts, 10777 and 78721, that added together give a palindrome (89498).

The spelling of 1077778721 in words is "one billion, seventy-seven million, seven hundred seventy-eight thousand, seven hundred twenty-one".