21765100900 has 27 divisors (see below), whose sum is σ = 47233470571. Its totient is φ = 8705450240.

The previous prime is 21765100897. The next prime is 21765100939. The reversal of 21765100900 is 900156712.

The square root of 21765100900 is 147530.

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

It can be written as a sum of positive squares in 4 ways, for example, as 493461796 + 21271639104 = 22214^2 + 145848^2 .

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, 1467924 + ... + 1482676.

Almost surely, 2^21765100900 is an apocalyptic number.

21765100900 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

21765100900 is the 147530-th square number.

It is an amenable number.

21765100900 is an abundant number, since it is smaller than the sum of its proper divisors (25468369671).

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

21765100900 is an frugal number, since it uses more digits than its factorization.

21765100900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29520 (or 14760 counting only the distinct ones).

The product of its (nonzero) digits is 3780, while the sum is 31.

The spelling of 21765100900 in words is "twenty-one billion, seven hundred sixty-five million, one hundred thousand, nine hundred".