20668921 has 8 divisors (see below), whose sum is σ = 25438784. Its totient is φ = 16353360.

The previous prime is 20668919. The next prime is 20668931. The reversal of 20668921 is 12986602.

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 20668921 - 2¹ = 20668919 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20668931) 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, 113475 + ... + 113656.

It is an arithmetic number, because the mean of its divisors is an integer number (3179848).

Almost surely, 2^20668921 is an apocalyptic number.

It is an amenable number.

20668921 is a deficient number, since it is larger than the sum of its proper divisors (4769863).

20668921 is a wasteful number, since it uses less digits than its factorization.

20668921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 227151.

The product of its (nonzero) digits is 10368, while the sum is 34.

The square root of 20668921 is about 4546.3085025106. The cubic root of 20668921 is about 274.4348548077.

The spelling of 20668921 in words is "twenty million, six hundred sixty-eight thousand, nine hundred twenty-one".