21550649400 has 288 divisors, whose sum is σ = 85778259840. Its totient is φ = 4925784960.

The previous prime is 21550649381. The next prime is 21550649401. The reversal of 21550649400 is 494605512.

21550649400 is a `hidden beast` number, since 2 + 1 + 5 + 5 + 0 + 649 + 4 + 0 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21550649401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 308527 + ... + 371873.

It is an arithmetic number, because the mean of its divisors is an integer number (297841180).

Almost surely, 2^21550649400 is an apocalyptic number.

21550649400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21550649400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (42889129920).

21550649400 is an abundant number, since it is smaller than the sum of its proper divisors (64227610440).

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

21550649400 is a wasteful number, since it uses less digits than its factorization.

21550649400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63385 (or 63364 counting only the distinct ones).

The product of its (nonzero) digits is 43200, while the sum is 36.

The spelling of 21550649400 in words is "twenty-one billion, five hundred fifty million, six hundred forty-nine thousand, four hundred".