9780221025 has 81 divisors (see below), whose sum is σ = 18541392051. Its totient is φ = 4927344480.

The previous prime is 9780220999. The next prime is 9780221027. The reversal of 9780221025 is 5201220879.

The square root of 9780221025 is 98895.

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., 3520879569 + 6259341456 = 59337^2 + 79116^2 .

It is not a de Polignac number, because 9780221025 - 2⁵ = 9780220993 is a prime.

It is not an unprimeable number, because it can be changed into a prime (9780221027) by changing a digit.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 28184902 + ... + 28185248.

Almost surely, 2^9780221025 is an apocalyptic number.

9780221025 is a gapful number since it is divisible by the number (95) formed by its first and last digit.

9780221025 is the 98895-th square number.

9780221025 is the 49448-th centered octagonal number.

It is an amenable number.

9780221025 is a deficient number, since it is larger than the sum of its proper divisors (8761171026).

9780221025 is a wasteful number, since it uses less digits than its factorization.

9780221025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 748 (or 374 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 36.

The cubic root of 9780221025 is about 2138.5343142401.

Multiplying 9780221025 by its sum of digits (36), we get a square (352087956900 = 593370²).

The spelling of 9780221025 in words is "nine billion, seven hundred eighty million, two hundred twenty-one thousand, twenty-five".