20006921 has 8 divisors (see below), whose sum is σ = 21873888. Its totient is φ = 18148000.

The previous prime is 20006887. The next prime is 20006923. The reversal of 20006921 is 12960002.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20006921 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 20006893 and 20006902.

It is not an unprimeable number, because it can be changed into a prime (20006923) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3986 + ... + 7476.

It is an arithmetic number, because the mean of its divisors is an integer number (2734236).

Almost surely, 2^20006921 is an apocalyptic number.

It is an amenable number.

20006921 is a deficient number, since it is larger than the sum of its proper divisors (1866967).

20006921 is a wasteful number, since it uses less digits than its factorization.

20006921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4023.

The product of its (nonzero) digits is 216, while the sum is 20.

The square root of 20006921 is about 4472.9096793922. The cubic root of 20006921 is about 271.4730688557.

Adding to 20006921 its reverse (12960002), we get a palindrome (32966923).

The spelling of 20006921 in words is "twenty million, six thousand, nine hundred twenty-one".