1681946749 has 4 divisors (see below), whose sum is σ = 1922224864. Its totient is φ = 1441668636.

The previous prime is 1681946741. The next prime is 1681946759. The reversal of 1681946749 is 9476491861.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1681946749 - 2³ = 1681946741 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1681946749.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1681946741) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 120139047 + ... + 120139060.

It is an arithmetic number, because the mean of its divisors is an integer number (480556216).

Almost surely, 2^1681946749 is an apocalyptic number.

It is an amenable number.

1681946749 is a deficient number, since it is larger than the sum of its proper divisors (240278115).

1681946749 is an equidigital number, since it uses as much as digits as its factorization.

1681946749 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 240278114.

The product of its digits is 2612736, while the sum is 55.

The square root of 1681946749 is about 41011.5440943157. The cubic root of 1681946749 is about 1189.2433928326.

It can be divided in two parts, 1681946 and 749, that added together give a triangular number (1682695 = T₁₈₃₄).

The spelling of 1681946749 in words is "one billion, six hundred eighty-one million, nine hundred forty-six thousand, seven hundred forty-nine".