99987861 has 8 divisors (see below), whose sum is σ = 140333920. Its totient is φ = 63150192.

The previous prime is 99987817. The next prime is 99987869. The reversal of 99987861 is 16878999.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 99987861 - 2¹⁷ = 99856789 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (57), and also a Moran number because the ratio is a prime number: 1754173 = 99987861 / (9 + 9 + 9 + 8 + 7 + 8 + 6 + 1).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (99987869) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 877030 + ... + 877143.

It is an arithmetic number, because the mean of its divisors is an integer number (17541740).

Almost surely, 2^99987861 is an apocalyptic number.

It is an amenable number.

99987861 is a deficient number, since it is larger than the sum of its proper divisors (40346059).

99987861 is a wasteful number, since it uses less digits than its factorization.

99987861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1754195.

The product of its digits is 1959552, while the sum is 57.

The square root of 99987861 is about 9999.3930315795. The cubic root of 99987861 is about 464.1401011857.

The spelling of 99987861 in words is "ninety-nine million, nine hundred eighty-seven thousand, eight hundred sixty-one".