9940423661 has 16 divisors (see below), whose sum is σ = 11603904000. Its totient is φ = 8511857424.

The previous prime is 9940423643. The next prime is 9940423679. The reversal of 9940423661 is 1663240499.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (9940423643) and next prime (9940423679).

It is a de Polignac number, because none of the positive numbers 2^k-9940423661 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9940423631) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 342431 + ... + 370323.

It is an arithmetic number, because the mean of its divisors is an integer number (725244000).

Almost surely, 2^9940423661 is an apocalyptic number.

It is an amenable number.

9940423661 is a deficient number, since it is larger than the sum of its proper divisors (1663480339).

9940423661 is a wasteful number, since it uses less digits than its factorization.

9940423661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28953 (or 28939 counting only the distinct ones).

The product of its (nonzero) digits is 279936, while the sum is 44.

The square root of 9940423661 is about 99701.6733109330. The cubic root of 9940423661 is about 2150.1477209481.

The spelling of 9940423661 in words is "nine billion, nine hundred forty million, four hundred twenty-three thousand, six hundred sixty-one".