66726557 has 8 divisors (see below), whose sum is σ = 68462520. Its totient is φ = 64995840.

The previous prime is 66726551. The next prime is 66726563. The reversal of 66726557 is 75562766.

It is an interprime number because it is at equal distance from previous prime (66726551) and next prime (66726563).

It can be written as a sum of positive squares in 4 ways, for example, as 5480281 + 61246276 = 2341^2 + 7826^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 66726557 - 2⁶ = 66726493 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 (66726551) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 44069 + ... + 45557.

It is an arithmetic number, because the mean of its divisors is an integer number (8557815).

Almost surely, 2^66726557 is an apocalyptic number.

It is an amenable number.

66726557 is a deficient number, since it is larger than the sum of its proper divisors (1735963).

66726557 is a wasteful number, since it uses less digits than its factorization.

66726557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2623.

The product of its digits is 529200, while the sum is 44.

The square root of 66726557 is about 8168.6325048933. The cubic root of 66726557 is about 405.6015183981.

The spelling of 66726557 in words is "sixty-six million, seven hundred twenty-six thousand, five hundred fifty-seven".