21540553650 has 288 divisors, whose sum is σ = 75952281600. Its totient is φ = 4240252800.

The previous prime is 21540553649. The next prime is 21540553651. The reversal of 21540553650 is 5635504512.

21540553650 is a `hidden beast` number, since 2 + 1 + 5 + 40 + 553 + 65 + 0 = 666.

It is an interprime number because it is at equal distance from previous prime (21540553649) and next prime (21540553651).

It is not an unprimeable number, because it can be changed into a prime (21540553651) by changing a digit.

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 143 ways as a sum of consecutive naturals, for example, 641991 + ... + 674709.

It is an arithmetic number, because the mean of its divisors is an integer number (263723200).

Almost surely, 2^21540553650 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21540553650, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37976140800).

21540553650 is an abundant number, since it is smaller than the sum of its proper divisors (54411727950).

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

21540553650 is a wasteful number, since it uses less digits than its factorization.

21540553650 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32774 (or 32766 counting only the distinct ones).

The product of its (nonzero) digits is 90000, while the sum is 36.

The spelling of 21540553650 in words is "twenty-one billion, five hundred forty million, five hundred fifty-three thousand, six hundred fifty".