21533402 has 24 divisors (see below), whose sum is σ = 35895636. Its totient is φ = 9680000.

The previous prime is 21533363. The next prime is 21533431. The reversal of 21533402 is 20433512.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 21242881 + 290521 = 4609^2 + 539^2 .

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 24002 + ... + 24882.

Almost surely, 2^21533402 is an apocalyptic number.

21533402 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

21533402 is a deficient number, since it is larger than the sum of its proper divisors (14362234).

21533402 is a wasteful number, since it uses less digits than its factorization.

21533402 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1006 (or 995 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 20.

The square root of 21533402 is about 4640.4096801899. The cubic root of 21533402 is about 278.2088126315.

Adding to 21533402 its reverse (20433512), we get a palindrome (41966914).

It can be divided in two parts, 2153 and 3402, that added together give a palindrome (5555).

The spelling of 21533402 in words is "twenty-one million, five hundred thirty-three thousand, four hundred two".