99381621 has 4 divisors (see below), whose sum is σ = 132508832. Its totient is φ = 66254412.

The previous prime is 99381619. The next prime is 99381631. The reversal of 99381621 is 12618399.

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.

It is not a de Polignac number, because 99381621 - 2¹ = 99381619 is a prime.

It is a super-3 number, since 3×99381621³ (a number of 25 digits) contains 333 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 99381621.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (99381631) 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, 16563601 + ... + 16563606.

It is an arithmetic number, because the mean of its divisors is an integer number (33127208).

Almost surely, 2^99381621 is an apocalyptic number.

It is an amenable number.

99381621 is a deficient number, since it is larger than the sum of its proper divisors (33127211).

99381621 is a wasteful number, since it uses less digits than its factorization.

99381621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33127210.

The product of its digits is 23328, while the sum is 39.

The square root of 99381621 is about 9969.0331025632. The cubic root of 99381621 is about 463.2001507497.

The spelling of 99381621 in words is "ninety-nine million, three hundred eighty-one thousand, six hundred twenty-one".