20432921 has 4 divisors (see below), whose sum is σ = 20867712. Its totient is φ = 19998132.

The previous prime is 20432897. The next prime is 20432933. The reversal of 20432921 is 12923402.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20432921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20432981) 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, 217325 + ... + 217418.

It is an arithmetic number, because the mean of its divisors is an integer number (5216928).

Almost surely, 2^20432921 is an apocalyptic number.

It is an amenable number.

20432921 is a deficient number, since it is larger than the sum of its proper divisors (434791).

20432921 is an equidigital number, since it uses as much as digits as its factorization.

20432921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 434790.

The product of its (nonzero) digits is 864, while the sum is 23.

The square root of 20432921 is about 4520.2788630791. The cubic root of 20432921 is about 273.3863448968.

The spelling of 20432921 in words is "twenty million, four hundred thirty-two thousand, nine hundred twenty-one".