20857387 has 2 divisors, whose sum is σ = 20857388. Its totient is φ = 20857386.

The previous prime is 20857373. The next prime is 20857393. The reversal of 20857387 is 78375802.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20857387 - 2²³ = 12468779 is a prime.

It is not a weakly prime, because it can be changed into another prime (20857357) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10428693 + 10428694.

It is an arithmetic number, because the mean of its divisors is an integer number (10428694).

Almost surely, 2^20857387 is an apocalyptic number.

20857387 is a deficient number, since it is larger than the sum of its proper divisors (1).

20857387 is an equidigital number, since it uses as much as digits as its factorization.

20857387 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 94080, while the sum is 40.

The square root of 20857387 is about 4566.9888329183. The cubic root of 20857387 is about 275.2664612881.

The spelling of 20857387 in words is "twenty million, eight hundred fifty-seven thousand, three hundred eighty-seven".