21454537 has 4 divisors (see below), whose sum is σ = 23104900. Its totient is φ = 19804176.

The previous prime is 21454483. The next prime is 21454541. The reversal of 21454537 is 73545412.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2653641 + 18800896 = 1629^2 + 4336^2 .

It is a cyclic number.

It is not a de Polignac number, because 21454537 - 2⁷ = 21454409 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21454499 and 21454508.

It is not an unprimeable number, because it can be changed into a prime (21454547) 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, 825162 + ... + 825187.

It is an arithmetic number, because the mean of its divisors is an integer number (5776225).

Almost surely, 2^21454537 is an apocalyptic number.

It is an amenable number.

21454537 is a deficient number, since it is larger than the sum of its proper divisors (1650363).

21454537 is a wasteful number, since it uses less digits than its factorization.

21454537 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1650362.

The product of its digits is 16800, while the sum is 31.

The square root of 21454537 is about 4631.9042520329. The cubic root of 21454537 is about 277.8687552251.

Adding to 21454537 its reverse (73545412), we get a palindrome (94999949).

The spelling of 21454537 in words is "twenty-one million, four hundred fifty-four thousand, five hundred thirty-seven".