99667921 has 4 divisors (see below), whose sum is σ = 100550052. Its totient is φ = 98785792.

The previous prime is 99667907. The next prime is 99667951. The reversal of 99667921 is 12976699.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12976699 = 73 ⋅177763.

It can be written as a sum of positive squares in 2 ways, for example, as 6275025 + 93392896 = 2505^2 + 9664^2 .

It is a cyclic number.

It is not a de Polignac number, because 99667921 - 2¹⁷ = 99536849 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (99667951) 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, 440896 + ... + 441121.

It is an arithmetic number, because the mean of its divisors is an integer number (25137513).

Almost surely, 2^99667921 is an apocalyptic number.

It is an amenable number.

99667921 is a deficient number, since it is larger than the sum of its proper divisors (882131).

99667921 is a wasteful number, since it uses less digits than its factorization.

99667921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 882130.

The product of its digits is 367416, while the sum is 49.

The square root of 99667921 is about 9983.3822425068. The cubic root of 99667921 is about 463.6445221858.

The spelling of 99667921 in words is "ninety-nine million, six hundred sixty-seven thousand, nine hundred twenty-one".