20789257 has 4 divisors (see below), whose sum is σ = 20938960. Its totient is φ = 20639556.

The previous prime is 20789221. The next prime is 20789261. The reversal of 20789257 is 75298702.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 75298702 = 2 ⋅37649351.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20789257 is a prime.

It is a super-2 number, since 2×20789257² = 864386413224098, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (20789207) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 74643 + ... + 74920.

It is an arithmetic number, because the mean of its divisors is an integer number (5234740).

Almost surely, 2^20789257 is an apocalyptic number.

It is an amenable number.

20789257 is a deficient number, since it is larger than the sum of its proper divisors (149703).

20789257 is a wasteful number, since it uses less digits than its factorization.

20789257 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 149702.

The product of its (nonzero) digits is 70560, while the sum is 40.

The square root of 20789257 is about 4559.5237689917. The cubic root of 20789257 is about 274.9664179378.

The spelling of 20789257 in words is "twenty million, seven hundred eighty-nine thousand, two hundred fifty-seven".