7211121661 has 8 divisors (see below), whose sum is σ = 7607797920. Its totient is φ = 6816159792.

The previous prime is 7211121641. The next prime is 7211121679. The reversal of 7211121661 is 1661211127.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 7211121661 - 2²³ = 7202733053 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 (7211121641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 419950 + ... + 436783.

It is an arithmetic number, because the mean of its divisors is an integer number (950974740).

Almost surely, 2^7211121661 is an apocalyptic number.

It is an amenable number.

7211121661 is a deficient number, since it is larger than the sum of its proper divisors (396676259).

7211121661 is a wasteful number, since it uses less digits than its factorization.

7211121661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 857195.

The product of its digits is 1008, while the sum is 28.

The square root of 7211121661 is about 84918.3234702617. The cubic root of 7211121661 is about 1931.9725026878.

Adding to 7211121661 its reverse (1661211127), we get a palindrome (8872332788).

The spelling of 7211121661 in words is "seven billion, two hundred eleven million, one hundred twenty-one thousand, six hundred sixty-one".