21971532 has 48 divisors (see below), whose sum is σ = 58367232. Its totient is φ = 6367680.

The previous prime is 21971527. The next prime is 21971533. The reversal of 21971532 is 23517912.

It is a self number, because there is not a number n which added to its sum of digits gives 21971532.

It is not an unprimeable number, because it can be changed into a prime (21971533) 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 15 ways as a sum of consecutive naturals, for example, 583 + ... + 6654.

It is an arithmetic number, because the mean of its divisors is an integer number (1215984).

Almost surely, 2^21971532 is an apocalyptic number.

21971532 is a gapful number since it is divisible by the number (22) 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 21971532, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29183616).

21971532 is an abundant number, since it is smaller than the sum of its proper divisors (36395700).

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

21971532 is a wasteful number, since it uses less digits than its factorization.

21971532 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7278 (or 7276 counting only the distinct ones).

The product of its digits is 3780, while the sum is 30.

The square root of 21971532 is about 4687.3800784660. The cubic root of 21971532 is about 280.0830196001.

The spelling of 21971532 in words is "twenty-one million, nine hundred seventy-one thousand, five hundred thirty-two".