21537441 has 16 divisors (see below), whose sum is σ = 32771200. Its totient is φ = 13969584.

The previous prime is 21537427. The next prime is 21537473. The reversal of 21537441 is 14473512.

21537441 is a `hidden beast` number, since 215 + 3 + 7 + 441 = 666.

It is not a de Polignac number, because 21537441 - 2⁹ = 21536929 is a prime.

It is a super-2 number, since 2×21537441² = 927722729656962, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21537491) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9781 + ... + 11778.

It is an arithmetic number, because the mean of its divisors is an integer number (2048200).

Almost surely, 2^21537441 is an apocalyptic number.

It is an amenable number.

21537441 is a deficient number, since it is larger than the sum of its proper divisors (11233759).

21537441 is a wasteful number, since it uses less digits than its factorization.

21537441 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21605 (or 21599 counting only the distinct ones).

The product of its digits is 3360, while the sum is 27.

The square root of 21537441 is about 4640.8448584283. The cubic root of 21537441 is about 278.2262059993.

The spelling of 21537441 in words is "twenty-one million, five hundred thirty-seven thousand, four hundred forty-one".