9972091661 has 16 divisors (see below), whose sum is σ = 11647758336. Its totient is φ = 8359464816.

The previous prime is 9972091643. The next prime is 9972091691. The reversal of 9972091661 is 1661902799.

It is a cyclic number.

It is not a de Polignac number, because 9972091661 - 2¹⁰ = 9972090637 is a prime.

It is a super-2 number, since 2×9972091661² (a number of 21 digits) 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 (9972091631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 465590 + ... + 486536.

It is an arithmetic number, because the mean of its divisors is an integer number (727984896).

Almost surely, 2^9972091661 is an apocalyptic number.

It is an amenable number.

9972091661 is a deficient number, since it is larger than the sum of its proper divisors (1675666675).

9972091661 is a wasteful number, since it uses less digits than its factorization.

9972091661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22448.

The product of its (nonzero) digits is 367416, while the sum is 50.

The square root of 9972091661 is about 99860.3608094824. The cubic root of 9972091661 is about 2152.4285995283.

The spelling of 9972091661 in words is "nine billion, nine hundred seventy-two million, ninety-one thousand, six hundred sixty-one".