20400057 has 24 divisors (see below), whose sum is σ = 31012800. Its totient is φ = 12896928.

The previous prime is 20400049. The next prime is 20400059. The reversal of 20400057 is 75000402.

It is a happy number.

It is not a de Polignac number, because 20400057 - 2³ = 20400049 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20400059) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 28419 + ... + 29127.

It is an arithmetic number, because the mean of its divisors is an integer number (1292200).

Almost surely, 2^20400057 is an apocalyptic number.

It is an amenable number.

20400057 is a deficient number, since it is larger than the sum of its proper divisors (10612743).

20400057 is a wasteful number, since it uses less digits than its factorization.

20400057 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 877 (or 874 counting only the distinct ones).

The product of its (nonzero) digits is 280, while the sum is 18.

The square root of 20400057 is about 4516.6422262561. The cubic root of 20400057 is about 273.2396960969.

Adding to 20400057 its reverse (75000402), we get a palindrome (95400459).

The spelling of 20400057 in words is "twenty million, four hundred thousand, fifty-seven".