205421664 has 96 divisors (see below), whose sum is σ = 630685440. Its totient is φ = 57318912.

The previous prime is 205421651. The next prime is 205421677. The reversal of 205421664 is 466124502.

205421664 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (205421651) and next prime (205421677).

It is a tau number, because it is divible by the number of its divisors (96).

It is a zygodrome in base 2.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 25342 + ... + 32450.

It is an arithmetic number, because the mean of its divisors is an integer number (6569640).

Almost surely, 2^205421664 is an apocalyptic number.

205421664 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 205421664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (315342720).

205421664 is an abundant number, since it is smaller than the sum of its proper divisors (425263776).

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

205421664 is a wasteful number, since it uses less digits than its factorization.

205421664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7172 (or 7164 counting only the distinct ones).

The product of its (nonzero) digits is 11520, while the sum is 30.

The square root of 205421664 is about 14332.5386446365. The cubic root of 205421664 is about 590.0408513321.

The spelling of 205421664 in words is "two hundred five million, four hundred twenty-one thousand, six hundred sixty-four".