21250640260 has 24 divisors (see below), whose sum is σ = 44685327960. Its totient is φ = 8489021184.

The previous prime is 21250640251. The next prime is 21250640287. The reversal of 21250640260 is 6204605212.

It can be written as a sum of positive squares in 4 ways, for example, as 865654084 + 20384986176 = 29422^2 + 142776^2 .

It is a super-2 number, since 2×21250640260² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 686665 + ... + 716944.

It is an arithmetic number, because the mean of its divisors is an integer number (1861888665).

Almost surely, 2^21250640260 is an apocalyptic number.

21250640260 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21250640260 is an abundant number, since it is smaller than the sum of its proper divisors (23434687700).

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

21250640260 is a wasteful number, since it uses less digits than its factorization.

21250640260 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1404375 (or 1404373 counting only the distinct ones).

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

The spelling of 21250640260 in words is "twenty-one billion, two hundred fifty million, six hundred forty thousand, two hundred sixty".