21757956 has 48 divisors (see below), whose sum is σ = 55738368. Its totient is φ = 6551200.

The previous prime is 21757951. The next prime is 21757969. The reversal of 21757956 is 65975712.

It is not an unprimeable number, because it can be changed into a prime (21757951) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 24781 + ... + 25643.

It is an arithmetic number, because the mean of its divisors is an integer number (1161216).

Almost surely, 2^21757956 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21757956, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27869184).

21757956 is an abundant number, since it is smaller than the sum of its proper divisors (33980412).

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

21757956 is a wasteful number, since it uses less digits than its factorization.

21757956 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1072 (or 1070 counting only the distinct ones).

The product of its digits is 132300, while the sum is 42.

The square root of 21757956 is about 4664.5424212885. The cubic root of 21757956 is about 279.1725400809.

The spelling of 21757956 in words is "twenty-one million, seven hundred fifty-seven thousand, nine hundred fifty-six".