21571090641 has 15 divisors (see below), whose sum is σ = 32225455801. Its totient is φ = 14379845868.

The previous prime is 21571090571. The next prime is 21571090643. The reversal of 21571090641 is 14609017512.

The square root of 21571090641 is 146871.

It is a perfect power (a square), and thus also a powerful number.

21571090641 is a `hidden beast` number, since 2 + 1 + 5 + 7 + 1 + 0 + 9 + 0 + 641 = 666.

It is not a de Polignac number, because 21571090641 - 2⁹ = 21571090129 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21571090596 and 21571090605.

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 14 ways as a sum of consecutive naturals, for example, 1313680 + ... + 1329998.

Almost surely, 2^21571090641 is an apocalyptic number.

21571090641 is the 146871-st square number.

21571090641 is the 73436-th centered octagonal number.

It is an amenable number.

21571090641 is a deficient number, since it is larger than the sum of its proper divisors (10654365160).

21571090641 is an frugal number, since it uses more digits than its factorization.

21571090641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32650 (or 16322 counting only the distinct ones).

The product of its (nonzero) digits is 15120, while the sum is 36.

Multiplying 21571090641 by its sum of digits (36), we get a square (776559263076 = 881226²).

The spelling of 21571090641 in words is "twenty-one billion, five hundred seventy-one million, ninety thousand, six hundred forty-one".