685020551 has 4 divisors (see below), whose sum is σ = 685692504. Its totient is φ = 684348600.

The previous prime is 685020533. The next prime is 685020599. The reversal of 685020551 is 155020586.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-685020551 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (685010551) 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, 334445 + ... + 336486.

It is an arithmetic number, because the mean of its divisors is an integer number (171423126).

Almost surely, 2^685020551 is an apocalyptic number.

685020551 is a deficient number, since it is larger than the sum of its proper divisors (671953).

685020551 is a wasteful number, since it uses less digits than its factorization.

685020551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 671952.

The product of its (nonzero) digits is 12000, while the sum is 32.

The square root of 685020551 is about 26172.8972603340. The cubic root of 685020551 is about 881.5247974499.

The spelling of 685020551 in words is "six hundred eighty-five million, twenty thousand, five hundred fifty-one".