1678089721 has 12 divisors (see below), whose sum is σ = 2129524560. Its totient is φ = 1307601960.

The previous prime is 1678089701. The next prime is 1678089733. The reversal of 1678089721 is 1279808761.

It is not a de Polignac number, because 1678089721 - 2⁹ = 1678089209 is a prime.

It is a super-2 number, since 2×1678089721² = 5631970223451715682, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (49).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1678089701) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1556131 + ... + 1557208.

It is an arithmetic number, because the mean of its divisors is an integer number (177460380).

Almost surely, 2^1678089721 is an apocalyptic number.

1678089721 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1678089721 is a deficient number, since it is larger than the sum of its proper divisors (451434839).

1678089721 is a wasteful number, since it uses less digits than its factorization.

1678089721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3113364 (or 3113357 counting only the distinct ones).

The product of its (nonzero) digits is 338688, while the sum is 49.

The square root of 1678089721 is about 40964.4934180810. The cubic root of 1678089721 is about 1188.3336423127. Note that the first 3 decimals are identical.

The spelling of 1678089721 in words is "one billion, six hundred seventy-eight million, eighty-nine thousand, seven hundred twenty-one".