20561420242 has 32 divisors (see below), whose sum is σ = 33988896000. Its totient is φ = 9250988880.

The previous prime is 20561420237. The next prime is 20561420261. The reversal of 20561420242 is 24202416502.

It is a self number, because there is not a number n which added to its sum of digits gives 20561420242.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3525733 + ... + 3531559.

It is an arithmetic number, because the mean of its divisors is an integer number (1062153000).

Almost surely, 2^20561420242 is an apocalyptic number.

20561420242 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

20561420242 is a deficient number, since it is larger than the sum of its proper divisors (13427475758).

20561420242 is a wasteful number, since it uses less digits than its factorization.

20561420242 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7446.

The product of its (nonzero) digits is 7680, while the sum is 28.

Adding to 20561420242 its reverse (24202416502), we get a palindrome (44763836744).

The spelling of 20561420242 in words is "twenty billion, five hundred sixty-one million, four hundred twenty thousand, two hundred forty-two".