21649161600 has 576 divisors, whose sum is σ = 87427529280. Its totient is φ = 5246208000.

The previous prime is 21649161587. The next prime is 21649161607. The reversal of 21649161600 is 616194612.

21649161600 is a `hidden beast` number, since 2 + 1 + 6 + 49 + 1 + 6 + 1 + 600 = 666.

It is a tau number, because it is divible by the number of its divisors (576).

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 (21649161607) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 8552335 + ... + 8554865.

It is an arithmetic number, because the mean of its divisors is an integer number (151783905).

Almost surely, 2^21649161600 is an apocalyptic number.

21649161600 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 21649161600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43713764640).

21649161600 is an abundant number, since it is smaller than the sum of its proper divisors (65778367680).

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

21649161600 is a wasteful number, since it uses less digits than its factorization.

21649161600 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2581 (or 2552 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 36.

The spelling of 21649161600 in words is "twenty-one billion, six hundred forty-nine million, one hundred sixty-one thousand, six hundred".