21439987776 has 63 divisors (see below), whose sum is σ = 61463928253. Its totient is φ = 7145491200.

The previous prime is 21439987753. The next prime is 21439987783. The reversal of 21439987776 is 67778993412.

The square root of 21439987776 is 146424.

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

It can be written as a sum of positive squares in only one way, i.e., 13554547776 + 7885440000 = 116424^2 + 88800^2 .

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 3511126 + ... + 3517226.

Almost surely, 2^21439987776 is an apocalyptic number.

21439987776 is the 146424-th square number.

It is an amenable number.

21439987776 is an abundant number, since it is smaller than the sum of its proper divisors (40023940477).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21439987776 is an frugal number, since it uses more digits than its factorization.

21439987776 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12220 (or 6106 counting only the distinct ones).

The product of its digits is 32006016, while the sum is 63.

The spelling of 21439987776 in words is "twenty-one billion, four hundred thirty-nine million, nine hundred eighty-seven thousand, seven hundred seventy-six".