21771428500 has 24 divisors (see below), whose sum is σ = 47548800936. Its totient is φ = 8708571200.

The previous prime is 21771428473. The next prime is 21771428507. The reversal of 21771428500 is 582417712.

It can be written as a sum of positive squares in 4 ways, for example, as 168896016 + 21602532484 = 12996^2 + 146978^2 .

It is a super-2 number, since 2×21771428500² (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 21771428500.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21771428507) 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, 21770929 + ... + 21771928.

It is an arithmetic number, because the mean of its divisors is an integer number (1981200039).

Almost surely, 2^21771428500 is an apocalyptic number.

21771428500 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21771428500 is an abundant number, since it is smaller than the sum of its proper divisors (25777372436).

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

21771428500 is a wasteful number, since it uses less digits than its factorization.

21771428500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43542876 (or 43542864 counting only the distinct ones).

The product of its (nonzero) digits is 31360, while the sum is 37.

The spelling of 21771428500 in words is "twenty-one billion, seven hundred seventy-one million, four hundred twenty-eight thousand, five hundred".