1687551321 has 4 divisors (see below), whose sum is σ = 2250068432. Its totient is φ = 1125034212.

The previous prime is 1687551317. The next prime is 1687551361. The reversal of 1687551321 is 1231557861.

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.

It is not a de Polignac number, because 1687551321 - 2² = 1687551317 is a prime.

It is a super-2 number, since 2×1687551321² = 5695658922017690082, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1687551321.

It is not an unprimeable number, because it can be changed into a prime (1687551361) 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, 281258551 + ... + 281258556.

It is an arithmetic number, because the mean of its divisors is an integer number (562517108).

Almost surely, 2^1687551321 is an apocalyptic number.

It is an amenable number.

1687551321 is a deficient number, since it is larger than the sum of its proper divisors (562517111).

1687551321 is an equidigital number, since it uses as much as digits as its factorization.

1687551321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 562517110.

The product of its digits is 50400, while the sum is 39.

The square root of 1687551321 is about 41079.8164674576. The cubic root of 1687551321 is about 1190.5628580404.

The spelling of 1687551321 in words is "one billion, six hundred eighty-seven million, five hundred fifty-one thousand, three hundred twenty-one".