21355571771 has 8 divisors (see below), whose sum is σ = 21746232288. Its totient is φ = 20967408000.

The previous prime is 21355571693. The next prime is 21355571777. The reversal of 21355571771 is 17717555312.

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 21355571771 - 2¹⁴ = 21355555387 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21355571777) 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, 606920 + ... + 641141.

It is an arithmetic number, because the mean of its divisors is an integer number (2718279036).

Almost surely, 2^21355571771 is an apocalyptic number.

21355571771 is a deficient number, since it is larger than the sum of its proper divisors (390660517).

21355571771 is a wasteful number, since it uses less digits than its factorization.

21355571771 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1248373.

The product of its digits is 257250, while the sum is 44.

The spelling of 21355571771 in words is "twenty-one billion, three hundred fifty-five million, five hundred seventy-one thousand, seven hundred seventy-one".