18211502500 has 45 divisors (see below), whose sum is σ = 39839674567. Its totient is φ = 7281902000.

The previous prime is 18211502497. The next prime is 18211502521. The reversal of 18211502500 is 520511281.

The square root of 18211502500 is 134950.

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

It can be written as a sum of positive squares in 2 ways, for example, as 1427781796 + 16783720704 = 37786^2 + 129552^2 .

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 polite number, since it can be written in 14 ways as a sum of consecutive naturals, for example, 6746151 + ... + 6748849.

Almost surely, 2^18211502500 is an apocalyptic number.

18211502500 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

18211502500 is the 134950-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18211502500

18211502500 is an abundant number, since it is smaller than the sum of its proper divisors (21628172067).

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

18211502500 is an frugal number, since it uses more digits than its factorization.

18211502500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5422 (or 2706 counting only the distinct ones).

The product of its (nonzero) digits is 800, while the sum is 25.

Multiplying 18211502500 by its sum of digits (25), we get a square (455287562500 = 674750²).

18211502500 divided by its sum of digits (25) gives a square (728460100 = 26990²).

The spelling of 18211502500 in words is "eighteen billion, two hundred eleven million, five hundred two thousand, five hundred".