9999998621 has 16 divisors (see below), whose sum is σ = 11027612160. Its totient is φ = 9028373760.

The previous prime is 9999998611. The next prime is 9999998633. The reversal of 9999998621 is 1268999999.

It is a cyclic number.

It is not a de Polignac number, because 9999998621 - 2⁶ = 9999998557 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (71).

It is a Duffinian number.

It is a nialpdrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9999998611) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 67301 + ... + 156618.

It is an arithmetic number, because the mean of its divisors is an integer number (689225760).

Almost surely, 2^9999998621 is an apocalyptic number.

It is an amenable number.

9999998621 is a deficient number, since it is larger than the sum of its proper divisors (1027613539).

9999998621 is a wasteful number, since it uses less digits than its factorization.

9999998621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 224044.

The product of its digits is 51018336, while the sum is 71.

The square root of 9999998621 is about 99999.9931049998. The cubic root of 9999998621 is about 2154.4345909997.

The spelling of 9999998621 in words is "nine billion, nine hundred ninety-nine million, nine hundred ninety-eight thousand, six hundred twenty-one".