20421501 has 8 divisors (see below), whose sum is σ = 27493440. Its totient is φ = 13481952.

The previous prime is 20421497. The next prime is 20421503. The reversal of 20421501 is 10512402.

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

It is not a de Polignac number, because 20421501 - 2² = 20421497 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20421503) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 32736 + ... + 33353.

It is an arithmetic number, because the mean of its divisors is an integer number (3436680).

Almost surely, 2^20421501 is an apocalyptic number.

It is an amenable number.

20421501 is a deficient number, since it is larger than the sum of its proper divisors (7071939).

20421501 is a wasteful number, since it uses less digits than its factorization.

20421501 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66195.

The product of its (nonzero) digits is 80, while the sum is 15.

The square root of 20421501 is about 4519.0154901261. The cubic root of 20421501 is about 273.3354033487.

Adding to 20421501 its reverse (10512402), we get a palindrome (30933903).

Subtracting from 20421501 its reverse (10512402), we obtain a palindrome (9909099).

The spelling of 20421501 in words is "twenty million, four hundred twenty-one thousand, five hundred one".