61815566 has 4 divisors (see below), whose sum is σ = 92723352. Its totient is φ = 30907782.

The previous prime is 61815563. The next prime is 61815571. The reversal of 61815566 is 66551816.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61815563) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15453890 + ... + 15453893.

It is an arithmetic number, because the mean of its divisors is an integer number (23180838).

Almost surely, 2^61815566 is an apocalyptic number.

61815566 is a deficient number, since it is larger than the sum of its proper divisors (30907786).

61815566 is a wasteful number, since it uses less digits than its factorization.

61815566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30907785.

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

The square root of 61815566 is about 7862.2875805964. The cubic root of 61815566 is about 395.3963142994.

The spelling of 61815566 in words is "sixty-one million, eight hundred fifteen thousand, five hundred sixty-six".