1643456651 has 16 divisors (see below), whose sum is σ = 1783978560. Its totient is φ = 1509298560.

The previous prime is 1643456609. The next prime is 1643456663. The reversal of 1643456651 is 1566543461.

It is a cyclic number.

It is not a de Polignac number, because 1643456651 - 2²² = 1639262347 is a prime.

It is a super-2 number, since 2×1643456651² = 5401899527432271602, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1643456599 and 1643456608.

It is not an unprimeable number, because it can be changed into a prime (1643456681) 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, 113921 + ... + 127533.

It is an arithmetic number, because the mean of its divisors is an integer number (111498660).

Almost surely, 2^1643456651 is an apocalyptic number.

1643456651 is a deficient number, since it is larger than the sum of its proper divisors (140521909).

1643456651 is a wasteful number, since it uses less digits than its factorization.

1643456651 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13846.

The product of its digits is 259200, while the sum is 41.

The square root of 1643456651 is about 40539.5689542945. The cubic root of 1643456651 is about 1180.1016504885.

The spelling of 1643456651 in words is "one billion, six hundred forty-three million, four hundred fifty-six thousand, six hundred fifty-one".