99720638 has 4 divisors (see below), whose sum is σ = 149580960. Its totient is φ = 49860318.

The previous prime is 99720637. The next prime is 99720653. The reversal of 99720638 is 83602799.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 83602799 = 7 ⋅11943257.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (99720631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 24930158 + ... + 24930161.

It is an arithmetic number, because the mean of its divisors is an integer number (37395240).

Almost surely, 2^99720638 is an apocalyptic number.

99720638 is a deficient number, since it is larger than the sum of its proper divisors (49860322).

99720638 is a wasteful number, since it uses less digits than its factorization.

99720638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49860321.

The product of its (nonzero) digits is 163296, while the sum is 44.

The square root of 99720638 is about 9986.0221309589. The cubic root of 99720638 is about 463.7262523954.

The spelling of 99720638 in words is "ninety-nine million, seven hundred twenty thousand, six hundred thirty-eight".