1681221861 has 48 divisors (see below), whose sum is σ = 2689509888. Its totient is φ = 1003536000.

The previous prime is 1681221847. The next prime is 1681221881.

1681221861 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 1681221861 - 2⁷ = 1681221733 is a prime.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1681221811) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 2769420 + ... + 2770026.

It is an arithmetic number, because the mean of its divisors is an integer number (56031456).

Almost surely, 2^1681221861 is an apocalyptic number.

1681221861 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1681221861 is a deficient number, since it is larger than the sum of its proper divisors (1008288027).

1681221861 is a wasteful number, since it uses less digits than its factorization.

1681221861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1002 (or 999 counting only the distinct ones).

The product of its digits is 9216, while the sum is 36.

The square root of 1681221861 is about 41002.7055326841. The cubic root of 1681221861 is about 1189.0725209665.

The spelling of 1681221861 in words is "one billion, six hundred eighty-one million, two hundred twenty-one thousand, eight hundred sixty-one".