1681721763 has 16 divisors (see below), whose sum is σ = 2253636000. Its totient is φ = 1115493120.

The previous prime is 1681721761. The next prime is 1681721771. The reversal of 1681721763 is 3671271861.

It is not a de Polignac number, because 1681721763 - 2¹ = 1681721761 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1681721761) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 564943 + ... + 567911.

It is an arithmetic number, because the mean of its divisors is an integer number (140852250).

Almost surely, 2^1681721763 is an apocalyptic number.

1681721763 is a deficient number, since it is larger than the sum of its proper divisors (571914237).

1681721763 is a wasteful number, since it uses less digits than its factorization.

1681721763 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3862.

The product of its digits is 84672, while the sum is 42.

The square root of 1681721763 is about 41008.8010431907. The cubic root of 1681721763 is about 1189.1903639946.

The spelling of 1681721763 in words is "one billion, six hundred eighty-one million, seven hundred twenty-one thousand, seven hundred sixty-three".