21072544 has 24 divisors (see below), whose sum is σ = 42372288. Its totient is φ = 10311360.

The previous prime is 21072533. The next prime is 21072551. The reversal of 21072544 is 44527012.

It is a super-2 number, since 2×21072544² = 888104221263872, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5502 + ... + 8509.

It is an arithmetic number, because the mean of its divisors is an integer number (1765512).

Almost surely, 2^21072544 is an apocalyptic number.

It is an amenable number.

21072544 is an abundant number, since it is smaller than the sum of its proper divisors (21299744).

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

21072544 is a wasteful number, since it uses less digits than its factorization.

21072544 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14068 (or 14060 counting only the distinct ones).

The product of its (nonzero) digits is 2240, while the sum is 25.

The square root of 21072544 is about 4590.4840703351. The cubic root of 21072544 is about 276.2097404527.

Adding to 21072544 its reverse (44527012), we get a palindrome (65599556).

The spelling of 21072544 in words is "twenty-one million, seventy-two thousand, five hundred forty-four".