20878931 has 2 divisors, whose sum is σ = 20878932. Its totient is φ = 20878930.

The previous prime is 20878919. The next prime is 20878939. The reversal of 20878931 is 13987802.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20878931 - 2¹⁰ = 20877907 is a prime.

It is a super-2 number, since 2×20878931² = 871859519405522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (20878939) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10439465 + 10439466.

It is an arithmetic number, because the mean of its divisors is an integer number (10439466).

Almost surely, 2^20878931 is an apocalyptic number.

20878931 is a deficient number, since it is larger than the sum of its proper divisors (1).

20878931 is an equidigital number, since it uses as much as digits as its factorization.

20878931 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 24192, while the sum is 38.

The square root of 20878931 is about 4569.3468898739. The cubic root of 20878931 is about 275.3612046990.

The spelling of 20878931 in words is "twenty million, eight hundred seventy-eight thousand, nine hundred thirty-one".