8991021121 has 4 divisors (see below), whose sum is σ = 9009792000. Its totient is φ = 8972250244.

The previous prime is 8991021113. The next prime is 8991021131. The reversal of 8991021121 is 1211201998.

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: 1211201998 = 2 ⋅605600999.

It is a cyclic number.

It is not a de Polignac number, because 8991021121 - 2³ = 8991021113 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (8991021131) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9384721 + ... + 9385678.

It is an arithmetic number, because the mean of its divisors is an integer number (2252448000).

Almost surely, 2^8991021121 is an apocalyptic number.

It is an amenable number.

8991021121 is a deficient number, since it is larger than the sum of its proper divisors (18770879).

8991021121 is a wasteful number, since it uses less digits than its factorization.

8991021121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18770878.

The product of its (nonzero) digits is 2592, while the sum is 34.

The square root of 8991021121 is about 94820.9951487538. The cubic root of 8991021121 is about 2079.3918587779.

The spelling of 8991021121 in words is "eight billion, nine hundred ninety-one million, twenty-one thousand, one hundred twenty-one".