678761021 has 4 divisors (see below), whose sum is σ = 679837344. Its totient is φ = 677684700.

The previous prime is 678761011. The next prime is 678761029. The reversal of 678761021 is 120167876.

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 a cyclic number.

It is not a de Polignac number, because 678761021 - 2¹⁰ = 678759997 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (678761029) 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, 537215 + ... + 538476.

It is an arithmetic number, because the mean of its divisors is an integer number (169959336).

Almost surely, 2^678761021 is an apocalyptic number.

It is an amenable number.

678761021 is a deficient number, since it is larger than the sum of its proper divisors (1076323).

678761021 is a wasteful number, since it uses less digits than its factorization.

678761021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1076322.

The product of its (nonzero) digits is 28224, while the sum is 38.

The square root of 678761021 is about 26053.0424518903. The cubic root of 678761021 is about 878.8315333012.

The spelling of 678761021 in words is "six hundred seventy-eight million, seven hundred sixty-one thousand, twenty-one".