21503412 has 36 divisors (see below), whose sum is σ = 62121696. Its totient is φ = 6143760.

The previous prime is 21503399. The next prime is 21503423. The reversal of 21503412 is 21430512.

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

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, 42414 + ... + 42917.

Almost surely, 2^21503412 is an apocalyptic number.

It is an amenable number.

21503412 is an abundant number, since it is smaller than the sum of its proper divisors (40618284).

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

21503412 is a wasteful number, since it uses less digits than its factorization.

21503412 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 85348 (or 85343 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 21503412 is about 4637.1771585740. The cubic root of 21503412 is about 278.0795969651.

Adding to 21503412 its reverse (21430512), we get a palindrome (42933924).

Subtracting from 21503412 its reverse (21430512), we obtain a square (72900 = 270²).

The spelling of 21503412 in words is "twenty-one million, five hundred three thousand, four hundred twelve".