687828021 has 4 divisors (see below), whose sum is σ = 917104032. Its totient is φ = 458552012.

The previous prime is 687828019. The next prime is 687828023. The reversal of 687828021 is 120828786.

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 an interprime number because it is at equal distance from previous prime (687828019) and next prime (687828023).

It is a cyclic number.

It is not a de Polignac number, because 687828021 - 2¹ = 687828019 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (687828023) 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, 114638001 + ... + 114638006.

It is an arithmetic number, because the mean of its divisors is an integer number (229276008).

Almost surely, 2^687828021 is an apocalyptic number.

It is an amenable number.

687828021 is a deficient number, since it is larger than the sum of its proper divisors (229276011).

687828021 is a wasteful number, since it uses less digits than its factorization.

687828021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 229276010.

The product of its (nonzero) digits is 86016, while the sum is 42.

The square root of 687828021 is about 26226.4755733591. The cubic root of 687828021 is about 882.7274285911.

The spelling of 687828021 in words is "six hundred eighty-seven million, eight hundred twenty-eight thousand, twenty-one".