20121221042 has 16 divisors (see below), whose sum is σ = 33195076992. Its totient is φ = 9089127120.

The previous prime is 20121221041. The next prime is 20121221117. The reversal of 20121221042 is 24012212102.

It is a self number, because there is not a number n which added to its sum of digits gives 20121221042.

It is not an unprimeable number, because it can be changed into a prime (20121221041) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8231684 + ... + 8234127.

It is an arithmetic number, because the mean of its divisors is an integer number (2074692312).

Almost surely, 2^20121221042 is an apocalyptic number.

20121221042 is a deficient number, since it is larger than the sum of its proper divisors (13073855950).

20121221042 is a wasteful number, since it uses less digits than its factorization.

20121221042 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16465873.

The product of its (nonzero) digits is 128, while the sum is 17.

Adding to 20121221042 its reverse (24012212102), we get a palindrome (44133433144).

The spelling of 20121221042 in words is "twenty billion, one hundred twenty-one million, two hundred twenty-one thousand, forty-two".