21401533 has 4 divisors (see below), whose sum is σ = 21497728. Its totient is φ = 21305340.

The previous prime is 21401531. The next prime is 21401539. The reversal of 21401533 is 33510412.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21401533 - 2¹ = 21401531 is a prime.

It is a super-2 number, since 2×21401533² = 916051229500178, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21401533.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21401531) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 47763 + ... + 48208.

It is an arithmetic number, because the mean of its divisors is an integer number (5374432).

Almost surely, 2^21401533 is an apocalyptic number.

It is an amenable number.

21401533 is a deficient number, since it is larger than the sum of its proper divisors (96195).

21401533 is an equidigital number, since it uses as much as digits as its factorization.

21401533 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 96194.

The product of its (nonzero) digits is 360, while the sum is 19.

The square root of 21401533 is about 4626.1790929448. The cubic root of 21401533 is about 277.6397391598.

Adding to 21401533 its reverse (33510412), we get a palindrome (54911945).

The spelling of 21401533 in words is "twenty-one million, four hundred one thousand, five hundred thirty-three".