21071052661 has 8 divisors (see below), whose sum is σ = 21369206144. Its totient is φ = 20773156320.

The previous prime is 21071052631. The next prime is 21071052701. The reversal of 21071052661 is 16625017012.

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 21071052661 - 2¹¹ = 21071050613 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 (21071052631) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 103846 + ... + 230056.

It is an arithmetic number, because the mean of its divisors is an integer number (2671150768).

Almost surely, 2^21071052661 is an apocalyptic number.

It is an amenable number.

21071052661 is a deficient number, since it is larger than the sum of its proper divisors (298153483).

21071052661 is a wasteful number, since it uses less digits than its factorization.

21071052661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128571.

The product of its (nonzero) digits is 5040, while the sum is 31.

Adding to 21071052661 its reverse (16625017012), we get a palindrome (37696069673).

The spelling of 21071052661 in words is "twenty-one billion, seventy-one million, fifty-two thousand, six hundred sixty-one".