61666551 has 6 divisors (see below), whose sum is σ = 89073920. Its totient is φ = 41111028.

The previous prime is 61666543. The next prime is 61666559. The reversal of 61666551 is 15566616.

It is an interprime number because it is at equal distance from previous prime (61666543) and next prime (61666559).

It is not a de Polignac number, because 61666551 - 2³ = 61666543 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 (61666559) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 3425911 + ... + 3425928.

Almost surely, 2^61666551 is an apocalyptic number.

61666551 is a deficient number, since it is larger than the sum of its proper divisors (27407369).

61666551 is a wasteful number, since it uses less digits than its factorization.

61666551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6851845 (or 6851842 counting only the distinct ones).

The product of its digits is 32400, while the sum is 36.

The square root of 61666551 is about 7852.8052949249. The cubic root of 61666551 is about 395.0783394266.

The spelling of 61666551 in words is "sixty-one million, six hundred sixty-six thousand, five hundred fifty-one".