21504156 has 12 divisors (see below), whose sum is σ = 50176392. Its totient is φ = 7168048.

The previous prime is 21504151. The next prime is 21504157. The reversal of 21504156 is 65140512.

It is a tau number, because it is divible by the number of its divisors (12).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21504151) 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, 895995 + ... + 896018.

It is an arithmetic number, because the mean of its divisors is an integer number (4181366).

Almost surely, 2^21504156 is an apocalyptic number.

It is an amenable number.

21504156 is an abundant number, since it is smaller than the sum of its proper divisors (28672236).

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

21504156 is a wasteful number, since it uses less digits than its factorization.

21504156 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1792020 (or 1792018 counting only the distinct ones).

The product of its (nonzero) digits is 1200, while the sum is 24.

The square root of 21504156 is about 4637.2573790981. The cubic root of 21504156 is about 278.0828040349.

Adding to 21504156 its reverse (65140512), we get a palindrome (86644668).

The spelling of 21504156 in words is "twenty-one million, five hundred four thousand, one hundred fifty-six".