21257154440 has 16 divisors (see below), whose sum is σ = 47828597580. Its totient is φ = 8502861760.

The previous prime is 21257154439. The next prime is 21257154473. The reversal of 21257154440 is 4445175212.

It can be written as a sum of positive squares in 2 ways, for example, as 18566242564 + 2690911876 = 136258^2 + 51874^2 .

It is a super-2 number, since 2×21257154440² (a number of 21 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 21257154440.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 265714391 + ... + 265714470.

Almost surely, 2^21257154440 is an apocalyptic number.

21257154440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21257154440 is an abundant number, since it is smaller than the sum of its proper divisors (26571443140).

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

21257154440 is a wasteful number, since it uses less digits than its factorization.

21257154440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 531428872 (or 531428868 counting only the distinct ones).

The product of its (nonzero) digits is 44800, while the sum is 35.

The spelling of 21257154440 in words is "twenty-one billion, two hundred fifty-seven million, one hundred fifty-four thousand, four hundred forty".