9997781 has 4 divisors (see below), whose sum is σ = 10524000. Its totient is φ = 9471564.

The previous prime is 9997777. The next prime is 9997783. The reversal of 9997781 is 1877999.

9997781 is digitally balanced in base 2 and base 3, because in such bases it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1877999 = 103 ⋅18233.

It is a cyclic number.

It is not a de Polignac number, because 9997781 - 2² = 9997777 is a prime.

It is a super-2 number, since 2×9997781² = 199911249847922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9997783) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 263081 + ... + 263118.

It is an arithmetic number, because the mean of its divisors is an integer number (2631000).

Almost surely, 2^9997781 is an apocalyptic number.

It is an amenable number.

9997781 is a deficient number, since it is larger than the sum of its proper divisors (526219).

9997781 is a wasteful number, since it uses less digits than its factorization.

9997781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 526218.

The product of its digits is 285768, while the sum is 50.

The square root of 9997781 is about 3161.9267859962. The cubic root of 9997781 is about 215.4275321891.

The spelling of 9997781 in words is "nine million, nine hundred ninety-seven thousand, seven hundred eighty-one".