99861221 has 4 divisors (see below), whose sum is σ = 99994944. Its totient is φ = 99727500.

The previous prime is 99861211. The next prime is 99861233. The reversal of 99861221 is 12216899.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12216899 = 71 ⋅172069.

It is a cyclic number.

It is not a de Polignac number, because 99861221 - 2¹⁰ = 99860197 is a prime.

It is a super-2 number, since 2×99861221² = 19944526919221682, which contains 22 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 (99861211) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 65735 + ... + 67236.

It is an arithmetic number, because the mean of its divisors is an integer number (24998736).

Almost surely, 2^99861221 is an apocalyptic number.

It is an amenable number.

99861221 is a deficient number, since it is larger than the sum of its proper divisors (133723).

99861221 is a wasteful number, since it uses less digits than its factorization.

99861221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 133722.

The product of its digits is 15552, while the sum is 38.

The square root of 99861221 is about 9993.0586408767. The cubic root of 99861221 is about 463.9440656044.

The spelling of 99861221 in words is "ninety-nine million, eight hundred sixty-one thousand, two hundred twenty-one".