1681049921 has 4 divisors (see below), whose sum is σ = 1754139072. Its totient is φ = 1607960772.

The previous prime is 1681049917. The next prime is 1681049933. The reversal of 1681049921 is 1299401861.

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, and also an emirpimes, since its reverse is a distinct semiprime: 1299401861 = 6869 ⋅189169.

It is a cyclic number.

It is not a de Polignac number, because 1681049921 - 2² = 1681049917 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1681049521) 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, 36544541 + ... + 36544586.

It is an arithmetic number, because the mean of its divisors is an integer number (438534768).

Almost surely, 2^1681049921 is an apocalyptic number.

It is an amenable number.

1681049921 is a deficient number, since it is larger than the sum of its proper divisors (73089151).

1681049921 is an equidigital number, since it uses as much as digits as its factorization.

1681049921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 73089150.

The product of its (nonzero) digits is 31104, while the sum is 41.

The square root of 1681049921 is about 41000.6087881631. The cubic root of 1681049921 is about 1189.0319837627.

The spelling of 1681049921 in words is "one billion, six hundred eighty-one million, forty-nine thousand, nine hundred twenty-one".