681549977 has 2 divisors, whose sum is σ = 681549978. Its totient is φ = 681549976.

The previous prime is 681549959. The next prime is 681549983. The reversal of 681549977 is 779945186.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 535043161 + 146506816 = 23131^2 + 12104^2 .

It is a cyclic number.

It is not a de Polignac number, because 681549977 - 2²⁴ = 664772761 is a prime.

It is a super-2 number, since 2×681549977² = 929020742297401058, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (681549877) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 340774988 + 340774989.

It is an arithmetic number, because the mean of its divisors is an integer number (340774989).

Almost surely, 2^681549977 is an apocalyptic number.

It is an amenable number.

681549977 is a deficient number, since it is larger than the sum of its proper divisors (1).

681549977 is an equidigital number, since it uses as much as digits as its factorization.

681549977 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3810240, while the sum is 56.

The square root of 681549977 is about 26106.5121569313. The cubic root of 681549977 is about 880.0335631999.

The spelling of 681549977 in words is "six hundred eighty-one million, five hundred forty-nine thousand, nine hundred seventy-seven".