99709921 has 4 divisors (see below), whose sum is σ = 99732672. Its totient is φ = 99687172.

The previous prime is 99709901. The next prime is 99709933. The reversal of 99709921 is 12990799.

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: 12990799 = 71 ⋅182969.

It is a cyclic number.

It is not a de Polignac number, because 99709921 - 2⁷ = 99709793 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (99709901) 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, 2485 + ... + 14338.

It is an arithmetic number, because the mean of its divisors is an integer number (24933168).

Almost surely, 2^99709921 is an apocalyptic number.

It is an amenable number.

99709921 is a deficient number, since it is larger than the sum of its proper divisors (22751).

99709921 is a wasteful number, since it uses less digits than its factorization.

99709921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22750.

The product of its (nonzero) digits is 91854, while the sum is 46.

The square root of 99709921 is about 9985.4855164884. The cubic root of 99709921 is about 463.7096395444.

It can be divided in two parts, 9970 and 9921, that added together give a palindrome (19891).

The spelling of 99709921 in words is "ninety-nine million, seven hundred nine thousand, nine hundred twenty-one".