21532421 has 8 divisors (see below), whose sum is σ = 23355864. Its totient is φ = 19770880.

The previous prime is 21532417. The next prime is 21532499. The reversal of 21532421 is 12423512.

It can be written as a sum of positive squares in 4 ways, for example, as 829921 + 20702500 = 911^2 + 4550^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21532421 - 2² = 21532417 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21532393 and 21532402.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21534421) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14750 + ... + 16143.

It is an arithmetic number, because the mean of its divisors is an integer number (2919483).

Almost surely, 2^21532421 is an apocalyptic number.

It is an amenable number.

21532421 is a deficient number, since it is larger than the sum of its proper divisors (1823443).

21532421 is a wasteful number, since it uses less digits than its factorization.

21532421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30951.

The product of its digits is 480, while the sum is 20.

The square root of 21532421 is about 4640.3039771118. The cubic root of 21532421 is about 278.2045877689.

Adding to 21532421 its reverse (12423512), we get a palindrome (33955933).

The spelling of 21532421 in words is "twenty-one million, five hundred thirty-two thousand, four hundred twenty-one".