21450537 has 6 divisors (see below), whose sum is σ = 30984122. Its totient is φ = 14300352.

The previous prime is 21450523. The next prime is 21450553. The reversal of 21450537 is 73505412.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 15280281 + 6170256 = 3909^2 + 2484^2 .

It is not a de Polignac number, because 21450537 - 2⁴ = 21450521 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21450537.

It is not an unprimeable number, because it can be changed into a prime (21450137) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1191688 + ... + 1191705.

Almost surely, 2^21450537 is an apocalyptic number.

It is an amenable number.

21450537 is a deficient number, since it is larger than the sum of its proper divisors (9533585).

21450537 is a wasteful number, since it uses less digits than its factorization.

21450537 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2383399 (or 2383396 counting only the distinct ones).

The product of its (nonzero) digits is 4200, while the sum is 27.

The square root of 21450537 is about 4631.4724440506. The cubic root of 21450537 is about 277.8514854653.

Adding to 21450537 its reverse (73505412), we get a palindrome (94955949).

The spelling of 21450537 in words is "twenty-one million, four hundred fifty thousand, five hundred thirty-seven".