1667551681 has 16 divisors (see below), whose sum is σ = 1780107264. Its totient is φ = 1558451664.

The previous prime is 1667551673. The next prime is 1667551687. The reversal of 1667551681 is 1861557661.

It is not a de Polignac number, because 1667551681 - 2³ = 1667551673 is a prime.

It is a super-2 number, since 2×1667551681² = 5561457217611851522, which contains 22 as substring.

Its product of digits (302400) is a multiple of the sum of its prime divisors (2700).

It is not an unprimeable number, because it can be changed into a prime (1667551687) 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, 953650 + ... + 955396.

It is an arithmetic number, because the mean of its divisors is an integer number (111256704).

Almost surely, 2^1667551681 is an apocalyptic number.

It is an amenable number.

1667551681 is a deficient number, since it is larger than the sum of its proper divisors (112555583).

1667551681 is a wasteful number, since it uses less digits than its factorization.

1667551681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2700.

The product of its digits is 302400, while the sum is 46.

The square root of 1667551681 is about 40835.6667755040. Note that the first 3 decimals coincide. The cubic root of 1667551681 is about 1185.8409244656.

The spelling of 1667551681 in words is "one billion, six hundred sixty-seven million, five hundred fifty-one thousand, six hundred eighty-one".