991621024464 has 40 divisors (see below), whose sum is σ = 2927643025600. Its totient is φ = 283320292608.

The previous prime is 991621024447. The next prime is 991621024481. The reversal of 991621024464 is 464420126199.

It is an interprime number because it is at equal distance from previous prime (991621024447) and next prime (991621024481).

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1475626189 + ... + 1475626860.

It is an arithmetic number, because the mean of its divisors is an integer number (73191075640).

Almost surely, 2^991621024464 is an apocalyptic number.

It is an amenable number.

991621024464 is an abundant number, since it is smaller than the sum of its proper divisors (1936022001136).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

991621024464 is a wasteful number, since it uses less digits than its factorization.

991621024464 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2951253067 (or 2951253061 counting only the distinct ones).

The product of its (nonzero) digits is 746496, while the sum is 48.

The spelling of 991621024464 in words is "nine hundred ninety-one billion, six hundred twenty-one million, twenty-four thousand, four hundred sixty-four".