991021200111 has 10 divisors (see below), whose sum is σ = 1480414385472. Its totient is φ = 660680800020.

The previous prime is 991021200073. The next prime is 991021200119. The reversal of 991021200111 is 111002120199.

It is not a de Polignac number, because 991021200111 - 2¹⁷ = 991021069039 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991021200119) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 6117414735 + ... + 6117414896.

Almost surely, 2^991021200111 is an apocalyptic number.

991021200111 is a deficient number, since it is larger than the sum of its proper divisors (489393185361).

991021200111 is a wasteful number, since it uses less digits than its factorization.

991021200111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12234829643 (or 12234829634 counting only the distinct ones).

The product of its (nonzero) digits is 324, while the sum is 27.

The spelling of 991021200111 in words is "nine hundred ninety-one billion, twenty-one million, two hundred thousand, one hundred eleven".