20851641 has 16 divisors (see below), whose sum is σ = 31094400. Its totient is φ = 13809744.

The previous prime is 20851637. The next prime is 20851643. The reversal of 20851641 is 14615802.

It is not a de Polignac number, because 20851641 - 2² = 20851637 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20851643) 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, 1780 + ... + 6698.

It is an arithmetic number, because the mean of its divisors is an integer number (1943400).

Almost surely, 2^20851641 is an apocalyptic number.

It is an amenable number.

20851641 is a deficient number, since it is larger than the sum of its proper divisors (10242759).

20851641 is a wasteful number, since it uses less digits than its factorization.

20851641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5085 (or 5079 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 27.

The square root of 20851641 is about 4566.3597098783. The cubic root of 20851641 is about 275.2411812542.

The spelling of 20851641 in words is "twenty million, eight hundred fifty-one thousand, six hundred forty-one".