20387431 has 2 divisors, whose sum is σ = 20387432. Its totient is φ = 20387430.

The previous prime is 20387401. The next prime is 20387441. The reversal of 20387431 is 13478302.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20387431 - 2¹⁷ = 20256359 is a prime.

It is a super-2 number, since 2×20387431² = 831294685559522, 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 20387431.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20387401) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10193715 + 10193716.

It is an arithmetic number, because the mean of its divisors is an integer number (10193716).

Almost surely, 2^20387431 is an apocalyptic number.

20387431 is a deficient number, since it is larger than the sum of its proper divisors (1).

20387431 is an equidigital number, since it uses as much as digits as its factorization.

20387431 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4032, while the sum is 28.

The square root of 20387431 is about 4515.2442901797. The cubic root of 20387431 is about 273.1833133069.

The spelling of 20387431 in words is "twenty million, three hundred eighty-seven thousand, four hundred thirty-one".