66861551 has 8 divisors (see below), whose sum is σ = 71535600. Its totient is φ = 62303040.

The previous prime is 66861541. The next prime is 66861577. The reversal of 66861551 is 15516866.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66861551 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 (66861541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 27686 + ... + 30003.

It is an arithmetic number, because the mean of its divisors is an integer number (8941950).

Almost surely, 2^66861551 is an apocalyptic number.

66861551 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

66861551 is a deficient number, since it is larger than the sum of its proper divisors (4674049).

66861551 is a wasteful number, since it uses less digits than its factorization.

66861551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 57769.

The product of its digits is 43200, while the sum is 38.

The square root of 66861551 is about 8176.8912796979. The cubic root of 66861551 is about 405.8748572869.

The spelling of 66861551 in words is "sixty-six million, eight hundred sixty-one thousand, five hundred fifty-one".