21491532 has 18 divisors (see below), whose sum is σ = 54325908. Its totient is φ = 7163832.

The previous prime is 21491531. The next prime is 21491537. The reversal of 21491532 is 23519412.

It is a tau number, because it is divible by the number of its divisors (18).

It is a junction number, because it is equal to n+sod(n) for n = 21491496 and 21491505.

It is not an unprimeable number, because it can be changed into a prime (21491531) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 298458 + ... + 298529.

It is an arithmetic number, because the mean of its divisors is an integer number (3018106).

Almost surely, 2^21491532 is an apocalyptic number.

It is an amenable number.

21491532 is an abundant number, since it is smaller than the sum of its proper divisors (32834376).

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

21491532 is a wasteful number, since it uses less digits than its factorization.

21491532 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 596997 (or 596992 counting only the distinct ones).

The product of its digits is 2160, while the sum is 27.

The square root of 21491532 is about 4635.8960298954. The cubic root of 21491532 is about 278.0283772768.

The spelling of 21491532 in words is "twenty-one million, four hundred ninety-one thousand, five hundred thirty-two".