21771494890 has 16 divisors (see below), whose sum is σ = 41493908232. Its totient is φ = 8196327424.

The previous prime is 21771494881. The next prime is 21771494891. The reversal of 21771494890 is 9849417712.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 18308525481 + 3462969409 = 135309^2 + 58847^2 .

It is a super-2 number, since 2×21771494890² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21771494891) 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, 64033639 + ... + 64033978.

Almost surely, 2^21771494890 is an apocalyptic number.

21771494890 is a deficient number, since it is larger than the sum of its proper divisors (19722413342).

21771494890 is a wasteful number, since it uses less digits than its factorization.

21771494890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 128067641.

The product of its (nonzero) digits is 1016064, while the sum is 52.

The spelling of 21771494890 in words is "twenty-one billion, seven hundred seventy-one million, four hundred ninety-four thousand, eight hundred ninety".