21571090642 has 16 divisors (see below), whose sum is σ = 33160323672. Its totient is φ = 10517879680.

The previous prime is 21571090571. The next prime is 21571090643. The reversal of 21571090642 is 24609017512.

It is a Cunningham number, because it is equal to 146871²+1.

It can be written as a sum of positive squares in 4 ways, for example, as 12095820361 + 9475270281 = 109981^2 + 97341^2 .

It is not an unprimeable number, because it can be changed into a prime (21571090643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 134928 + ... + 247684.

Almost surely, 2^21571090642 is an apocalyptic number.

21571090642 is a deficient number, since it is larger than the sum of its proper divisors (11589233030).

21571090642 is a wasteful number, since it uses less digits than its factorization.

21571090642 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 115133.

The product of its (nonzero) digits is 30240, while the sum is 37.

The spelling of 21571090642 in words is "twenty-one billion, five hundred seventy-one million, ninety thousand, six hundred forty-two".