667621523 has 4 divisors (see below), whose sum is σ = 669768528. Its totient is φ = 665474520.

The previous prime is 667621517. The next prime is 667621543. The reversal of 667621523 is 325126766.

667621523 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 325126766 = 2 ⋅162563383.

It is a cyclic number.

It is not a de Polignac number, because 667621523 - 2⁶ = 667621459 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (667621543) 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, 1073036 + ... + 1073657.

It is an arithmetic number, because the mean of its divisors is an integer number (167442132).

Almost surely, 2^667621523 is an apocalyptic number.

667621523 is a deficient number, since it is larger than the sum of its proper divisors (2147005).

667621523 is a wasteful number, since it uses less digits than its factorization.

667621523 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2147004.

The product of its digits is 90720, while the sum is 38.

The square root of 667621523 is about 25838.3730718480. The cubic root of 667621523 is about 873.9973376924.

The spelling of 667621523 in words is "six hundred sixty-seven million, six hundred twenty-one thousand, five hundred twenty-three".