20121231420 has 72 divisors (see below), whose sum is σ = 64246749840. Its totient is φ = 5083257600.

The previous prime is 20121231409. The next prime is 20121231437. The reversal of 20121231420 is 2413212102.

It is a happy number.

20121231420 is a `hidden beast` number, since 2 + 0 + 1 + 212 + 31 + 420 = 666.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 20121231393 and 20121231402.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2938281 + ... + 2945120.

It is an arithmetic number, because the mean of its divisors is an integer number (892315970).

Almost surely, 2^20121231420 is an apocalyptic number.

20121231420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20121231420 is an abundant number, since it is smaller than the sum of its proper divisors (44125518420).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20121231420 is a wasteful number, since it uses less digits than its factorization.

20121231420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5883435 (or 5883430 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

Adding to 20121231420 its reverse (2413212102), we get a palindrome (22534443522).

The spelling of 20121231420 in words is "twenty billion, one hundred twenty-one million, two hundred thirty-one thousand, four hundred twenty".