2687205721 has 2 divisors, whose sum is σ = 2687205722. Its totient is φ = 2687205720.

The previous prime is 2687205709. The next prime is 2687205737. The reversal of 2687205721 is 1275027862.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 2042045721 + 645160000 = 45189^2 + 25400^2 .

It is a cyclic number.

It is not a de Polignac number, because 2687205721 - 2²⁷ = 2552987993 is a prime.

It is not a weakly prime, because it can be changed into another prime (2687205761) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1343602860 + 1343602861.

It is an arithmetic number, because the mean of its divisors is an integer number (1343602861).

Almost surely, 2^2687205721 is an apocalyptic number.

It is an amenable number.

2687205721 is a deficient number, since it is larger than the sum of its proper divisors (1).

2687205721 is an equidigital number, since it uses as much as digits as its factorization.

2687205721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 94080, while the sum is 40.

The square root of 2687205721 is about 51838.2650269085. The cubic root of 2687205721 is about 1390.2736933238.

The spelling of 2687205721 in words is "two billion, six hundred eighty-seven million, two hundred five thousand, seven hundred twenty-one".