21771002500 has 135 divisors (see below), whose sum is σ = 51780859977. Its totient is φ = 8003112000.

The previous prime is 21771002479. The next prime is 21771002531. The reversal of 21771002500 is 520017712.

It is a happy number.

The square root of 21771002500 is 147550.

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

It can be written as a sum of positive squares in 7 ways, for example, as 21503876164 + 267126336 = 146642^2 + 16344^2 .

It is a Harshad number since it is a multiple of its sum of digits (25).

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 95907387 + ... + 95907613.

Almost surely, 2^21771002500 is an apocalyptic number.

21771002500 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

21771002500 is the 147550-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21771002500

21771002500 is an abundant number, since it is smaller than the sum of its proper divisors (30009857477).

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

21771002500 is an equidigital number, since it uses as much as digits as its factorization.

21771002500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 504 (or 247 counting only the distinct ones).

The product of its (nonzero) digits is 980, while the sum is 25.

Multiplying 21771002500 by its sum of digits (25), we get a square (544275062500 = 737750²).

21771002500 divided by its sum of digits (25) gives a square (870840100 = 29510²).

The spelling of 21771002500 in words is "twenty-one billion, seven hundred seventy-one million, two thousand, five hundred".