20421545 has 8 divisors (see below), whose sum is σ = 24535680. Its totient is φ = 16317360.

The previous prime is 20421503. The next prime is 20421553. The reversal of 20421545 is 54512402.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 20421545 - 2¹⁸ = 20159401 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 20421545.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3230 + ... + 7160.

It is an arithmetic number, because the mean of its divisors is an integer number (3066960).

Almost surely, 2^20421545 is an apocalyptic number.

It is an amenable number.

20421545 is a deficient number, since it is larger than the sum of its proper divisors (4114135).

20421545 is a wasteful number, since it uses less digits than its factorization.

20421545 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4975.

The product of its (nonzero) digits is 1600, while the sum is 23.

The square root of 20421545 is about 4519.0203584405. The cubic root of 20421545 is about 273.3355996573.

Adding to 20421545 its reverse (54512402), we get a palindrome (74933947).

The spelling of 20421545 in words is "twenty million, four hundred twenty-one thousand, five hundred forty-five".