61661551 has 12 divisors (see below), whose sum is σ = 74848752. Its totient is φ = 50553888.

The previous prime is 61661539. The next prime is 61661617. The reversal of 61661551 is 15516616.

It is not a de Polignac number, because 61661551 - 2⁵ = 61661519 is a prime.

It is a super-3 number, since 3×61661551³ (a number of 24 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61661521) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 26230 + ... + 28483.

It is an arithmetic number, because the mean of its divisors is an integer number (6237396).

Almost surely, 2^61661551 is an apocalyptic number.

61661551 is a deficient number, since it is larger than the sum of its proper divisors (13187201).

61661551 is a wasteful number, since it uses less digits than its factorization.

61661551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54750 (or 54743 counting only the distinct ones).

The product of its digits is 5400, while the sum is 31.

The square root of 61661551 is about 7852.4869309028. The cubic root of 61661551 is about 395.0676613250.

The spelling of 61661551 in words is "sixty-one million, six hundred sixty-one thousand, five hundred fifty-one".