20871951 has 4 divisors (see below), whose sum is σ = 27829272. Its totient is φ = 13914632.

The previous prime is 20871923. The next prime is 20871973. The reversal of 20871951 is 15917802.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20871951 - 2⁶ = 20871887 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20871251) 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, 3478656 + ... + 3478661.

It is an arithmetic number, because the mean of its divisors is an integer number (6957318).

Almost surely, 2^20871951 is an apocalyptic number.

20871951 is a deficient number, since it is larger than the sum of its proper divisors (6957321).

20871951 is an equidigital number, since it uses as much as digits as its factorization.

20871951 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6957320.

The product of its (nonzero) digits is 5040, while the sum is 33.

The square root of 20871951 is about 4568.5830407250. The cubic root of 20871951 is about 275.3305160999.

The spelling of 20871951 in words is "twenty million, eight hundred seventy-one thousand, nine hundred fifty-one".