• Equal to 31621², 999887641 is almost surely the largest square with non-increasing digits (excluding trailing zeros).

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999887641 has 9 divisors (see below), whose sum is σ = 1012989141. Its totient is φ = 986954652.

The previous prime is 999887633. The next prime is 999887653. The reversal of 999887641 is 146788999.

The square root of 999887641 is 31621.

It is a perfect power (a square), and thus also a powerful number.

999887641 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 999887641 - 2³ = 999887633 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 10.

It is a self number, because there is not a number n which added to its sum of digits gives 999887641.

It is not an unprimeable number, because it can be changed into a prime (999887611) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 3256810 + ... + 3257116.

It is an arithmetic number, because the mean of its divisors is an integer number (112554349).

Almost surely, 2^999887641 is an apocalyptic number.

999887641 is the 31621-st square number.

999887641 is the 15811-st centered octagonal number.

It is an amenable number.

999887641 is a deficient number, since it is larger than the sum of its proper divisors (13101500).

999887641 is an frugal number, since it uses more digits than its factorization.

999887641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 820 (or 410 counting only the distinct ones).

The product of its digits is 7838208, while the sum is 61.

The cubic root of 999887641 is about 999.9625455972.

The spelling of 999887641 in words is "nine hundred ninety-nine million, eight hundred eighty-seven thousand, six hundred forty-one".