9971820 has 36 divisors (see below), whose sum is σ = 30248400. Its totient is φ = 2659104.

The previous prime is 9971807. The next prime is 9971837. The reversal of 9971820 is 281799.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (36).

It is a super-2 number, since 2×9971820² = 198874388224800, which contains 22 as substring.

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

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 27520 + ... + 27879.

Almost surely, 2^9971820 is an apocalyptic number.

9971820 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

It is an amenable number.

9971820 is an abundant number, since it is smaller than the sum of its proper divisors (20276580).

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

9971820 is a wasteful number, since it uses less digits than its factorization.

9971820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55414 (or 55409 counting only the distinct ones).

The product of its (nonzero) digits is 9072, while the sum is 36.

The square root of 9971820 is about 3157.8188675097. The cubic root of 9971820 is about 215.2409053772.

The spelling of 9971820 in words is "nine million, nine hundred seventy-one thousand, eight hundred twenty".