1649187681 has 8 divisors (see below), whose sum is σ = 2211202080. Its totient is φ = 1093315872.

The previous prime is 1649187671. The next prime is 1649187703. The reversal of 1649187681 is 1867819461.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1649187681 - 2¹⁰ = 1649186657 is a prime.

It is a super-2 number, since 2×1649187681² = 5439640014324315522, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1649187611) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1535020 + ... + 1536093.

It is an arithmetic number, because the mean of its divisors is an integer number (276400260).

Almost surely, 2^1649187681 is an apocalyptic number.

It is an amenable number.

1649187681 is a deficient number, since it is larger than the sum of its proper divisors (562014399).

1649187681 is a wasteful number, since it uses less digits than its factorization.

1649187681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3071295.

The product of its digits is 580608, while the sum is 51.

The square root of 1649187681 is about 40610.1918365329. The cubic root of 1649187681 is about 1181.4718015571.

The spelling of 1649187681 in words is "one billion, six hundred forty-nine million, one hundred eighty-seven thousand, six hundred eighty-one".