61666554 has 16 divisors (see below), whose sum is σ = 123428448. Its totient is φ = 20539632.

The previous prime is 61666543. The next prime is 61666559. The reversal of 61666554 is 45566616.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (61666559) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6604 + ... + 12920.

It is an arithmetic number, because the mean of its divisors is an integer number (7714278).

Almost surely, 2^61666554 is an apocalyptic number.

61666554 is an abundant number, since it is smaller than the sum of its proper divisors (61761894).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

61666554 is a wasteful number, since it uses less digits than its factorization.

61666554 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7949.

The product of its digits is 129600, while the sum is 39.

The square root of 61666554 is about 7852.8054859394. The cubic root of 61666554 is about 395.0783458333.

It can be divided in two parts, 6166 and 6554, that added together give a triangular number (12720 = T₁₅₉).

The spelling of 61666554 in words is "sixty-one million, six hundred sixty-six thousand, five hundred fifty-four".