20778523 has 4 divisors (see below), whose sum is σ = 20794680. Its totient is φ = 20762368.

The previous prime is 20778521. The next prime is 20778551. The reversal of 20778523 is 32587702.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20778523 - 2¹ = 20778521 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20778521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5965 + ... + 8782.

It is an arithmetic number, because the mean of its divisors is an integer number (5198670).

Almost surely, 2^20778523 is an apocalyptic number.

20778523 is a deficient number, since it is larger than the sum of its proper divisors (16157).

20778523 is a wasteful number, since it uses less digits than its factorization.

20778523 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16156.

The product of its (nonzero) digits is 23520, while the sum is 34.

The square root of 20778523 is about 4558.3465203953. The cubic root of 20778523 is about 274.9190858366.

The spelling of 20778523 in words is "twenty million, seven hundred seventy-eight thousand, five hundred twenty-three".