20671665 has 16 divisors (see below), whose sum is σ = 37799808. Its totient is φ = 9449856.

The previous prime is 20671661. The next prime is 20671723. The reversal of 20671665 is 56617602.

It is not a de Polignac number, because 20671665 - 2² = 20671661 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20671661) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 98332 + ... + 98541.

It is an arithmetic number, because the mean of its divisors is an integer number (2362488).

Almost surely, 2^20671665 is an apocalyptic number.

It is an amenable number.

20671665 is a deficient number, since it is larger than the sum of its proper divisors (17128143).

20671665 is a wasteful number, since it uses less digits than its factorization.

20671665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 196888.

The product of its (nonzero) digits is 15120, while the sum is 33.

The square root of 20671665 is about 4546.6102757989. The cubic root of 20671665 is about 274.4469989011.

The spelling of 20671665 in words is "twenty million, six hundred seventy-one thousand, six hundred sixty-five".