921385440 has 72 divisors (see below), whose sum is σ = 3144232728. Its totient is φ = 245702400.

The previous prime is 921385427. The next prime is 921385447. The reversal of 921385440 is 44583129.

It is a tau number, because it is divible by the number of its divisors (72).

It is a super-2 number, since 2×921385440² = 1697902258087987200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 921385395 and 921385404.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (921385447) by changing a digit.

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 11 ways as a sum of consecutive naturals, for example, 318486 + ... + 321365.

It is an arithmetic number, because the mean of its divisors is an integer number (43669899).

Almost surely, 2^921385440 is an apocalyptic number.

921385440 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

It is an amenable number.

921385440 is an abundant number, since it is smaller than the sum of its proper divisors (2222847288).

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

921385440 is a wasteful number, since it uses less digits than its factorization.

921385440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 639872 (or 639861 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 36.

The square root of 921385440 is about 30354.3314866264. The cubic root of 921385440 is about 973.0767927555.

The spelling of 921385440 in words is "nine hundred twenty-one million, three hundred eighty-five thousand, four hundred forty".