25151221520 has 20 divisors (see below), whose sum is σ = 58476590220. Its totient is φ = 10060488576.

The previous prime is 25151221483. The next prime is 25151221541. The reversal of 25151221520 is 2512215152.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 11437874704 + 13713346816 = 106948^2 + 117104^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a super-2 number, since 2×25151221520² (a number of 22 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 25151221520.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 157195055 + ... + 157195214.

It is an arithmetic number, because the mean of its divisors is an integer number (2923829511).

Almost surely, 2^25151221520 is an apocalyptic number.

25151221520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

25151221520 is an abundant number, since it is smaller than the sum of its proper divisors (33325368700).

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

25151221520 is a wasteful number, since it uses less digits than its factorization.

25151221520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 314390282 (or 314390276 counting only the distinct ones).

The product of its (nonzero) digits is 2000, while the sum is 26.

Adding to 25151221520 its reverse (2512215152), we get a palindrome (27663436672).

The spelling of 25151221520 in words is "twenty-five billion, one hundred fifty-one million, two hundred twenty-one thousand, five hundred twenty".