99561778 has 4 divisors (see below), whose sum is σ = 149342670. Its totient is φ = 49780888.

The previous prime is 99561773. The next prime is 99561823. The reversal of 99561778 is 87716599.

It is a happy number.

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

It can be written as a sum of positive squares in only one way, i.e., 95589729 + 3972049 = 9777^2 + 1993^2 .

It is not an unprimeable number, because it can be changed into a prime (99561773) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 24890443 + ... + 24890446.

Almost surely, 2^99561778 is an apocalyptic number.

99561778 is the 5334-th centered heptagonal number.

99561778 is a deficient number, since it is larger than the sum of its proper divisors (49780892).

99561778 is a wasteful number, since it uses less digits than its factorization.

99561778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49780891.

The product of its digits is 952560, while the sum is 52.

The square root of 99561778 is about 9978.0648424431. The cubic root of 99561778 is about 463.4798750914.

The spelling of 99561778 in words is "ninety-nine million, five hundred sixty-one thousand, seven hundred seventy-eight".