20921533 has 8 divisors (see below), whose sum is σ = 21457152. Its totient is φ = 20389776.

The previous prime is 20921519. The next prime is 20921623. The reversal of 20921533 is 33512902.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 20921533 - 2⁵ = 20921501 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20921498 and 20921507.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20922533) 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, 12216 + ... + 13822.

It is an arithmetic number, because the mean of its divisors is an integer number (2682144).

Almost surely, 2^20921533 is an apocalyptic number.

It is an amenable number.

20921533 is a deficient number, since it is larger than the sum of its proper divisors (535619).

20921533 is a wasteful number, since it uses less digits than its factorization.

20921533 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1931.

The product of its (nonzero) digits is 1620, while the sum is 25.

The square root of 20921533 is about 4574.0062308659. The cubic root of 20921533 is about 275.5483625625.

The spelling of 20921533 in words is "twenty million, nine hundred twenty-one thousand, five hundred thirty-three".