25721221680 has 960 divisors, whose sum is σ = 117982448640. Its totient is φ = 5024194560.

The previous prime is 25721221679. The next prime is 25721221681. The reversal of 25721221680 is 8612212752.

It is a happy number.

25721221680 is a `hidden beast` number, since 2 + 572 + 1 + 2 + 2 + 1 + 6 + 80 = 666.

It is an interprime number because it is at equal distance from previous prime (25721221679) and next prime (25721221681).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (25721221681) by changing a digit.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 31101427 + ... + 31102253.

It is an arithmetic number, because the mean of its divisors is an integer number (122898384).

Almost surely, 2^25721221680 is an apocalyptic number.

25721221680 is a gapful number since it is divisible by the number (20) 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 25721221680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (58991224320).

25721221680 is an abundant number, since it is smaller than the sum of its proper divisors (92261226960).

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

25721221680 is a wasteful number, since it uses less digits than its factorization.

25721221680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 895 (or 872 counting only the distinct ones).

The product of its (nonzero) digits is 26880, while the sum is 36.

The spelling of 25721221680 in words is "twenty-five billion, seven hundred twenty-one million, two hundred twenty-one thousand, six hundred eighty".