20279881 has 2 divisors, whose sum is σ = 20279882. Its totient is φ = 20279880.

The previous prime is 20279873. The next prime is 20279899. The reversal of 20279881 is 18897202.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13623481 + 6656400 = 3691^2 + 2580^2 .

It is a cyclic number.

It is not a de Polignac number, because 20279881 - 2³ = 20279873 is a prime.

It is a super-2 number, since 2×20279881² = 822547146748322, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 20279881.

It is not a weakly prime, because it can be changed into another prime (20279081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10139940 + 10139941.

It is an arithmetic number, because the mean of its divisors is an integer number (10139941).

Almost surely, 2^20279881 is an apocalyptic number.

It is an amenable number.

20279881 is a deficient number, since it is larger than the sum of its proper divisors (1).

20279881 is an equidigital number, since it uses as much as digits as its factorization.

20279881 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16128, while the sum is 37.

The square root of 20279881 is about 4503.3188872208. The cubic root of 20279881 is about 272.7020906412.

The spelling of 20279881 in words is "twenty million, two hundred seventy-nine thousand, eight hundred eighty-one".