205221820 has 12 divisors (see below), whose sum is σ = 430965864. Its totient is φ = 82088720.

The previous prime is 205221811. The next prime is 205221823. The reversal of 205221820 is 28122502.

It is a super-2 number, since 2×205221820² = 84231990808224800, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 205221791 and 205221800.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205221823) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5130526 + ... + 5130565.

It is an arithmetic number, because the mean of its divisors is an integer number (35913822).

Almost surely, 2^205221820 is an apocalyptic number.

205221820 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

205221820 is an abundant number, since it is smaller than the sum of its proper divisors (225744044).

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

205221820 is a wasteful number, since it uses less digits than its factorization.

205221820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10261100 (or 10261098 counting only the distinct ones).

The product of its (nonzero) digits is 640, while the sum is 22.

The square root of 205221820 is about 14325.5652593536. The cubic root of 205221820 is about 589.8494492822.

The spelling of 205221820 in words is "two hundred five million, two hundred twenty-one thousand, eight hundred twenty".