25221664 has 48 divisors (see below), whose sum is σ = 56306880. Its totient is φ = 11024640.

The previous prime is 25221653. The next prime is 25221667. The reversal of 25221664 is 46612252.

It is a super-3 number, since 3×25221664³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is not an unprimeable number, because it can be changed into a prime (25221667) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6309 + ... + 9499.

It is an arithmetic number, because the mean of its divisors is an integer number (1173060).

Almost surely, 2^25221664 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 25221664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28153440).

25221664 is an abundant number, since it is smaller than the sum of its proper divisors (31085216).

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

25221664 is a wasteful number, since it uses less digits than its factorization.

25221664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3233 (or 3225 counting only the distinct ones).

The product of its digits is 5760, while the sum is 28.

The square root of 25221664 is about 5022.1174817003. The cubic root of 25221664 is about 293.2634314611.

It can be divided in two parts, 2522 and 1664, that added together give a triangular number (4186 = T₉₁).

The spelling of 25221664 in words is "twenty-five million, two hundred twenty-one thousand, six hundred sixty-four".