21601944 has 192 divisors, whose sum is σ = 75650400. Its totient is φ = 5660928.

The previous prime is 21601927. The next prime is 21601949. The reversal of 21601944 is 44910612.

It is a Harshad number since it is a multiple of its sum of digits (27).

21601944 is a modest number, since divided by 1944 gives 216 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21601949) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 137514 + ... + 137670.

Almost surely, 2^21601944 is an apocalyptic number.

21601944 is a gapful number since it is divisible by the number (24) 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 21601944, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37825200).

21601944 is an abundant number, since it is smaller than the sum of its proper divisors (54048456).

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

21601944 is a wasteful number, since it uses less digits than its factorization.

21601944 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 199 (or 182 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 21601944 is about 4647.7891518441. The cubic root of 21601944 is about 278.5036846260.

The spelling of 21601944 in words is "twenty-one million, six hundred one thousand, nine hundred forty-four".