1221401020 has 24 divisors (see below), whose sum is σ = 2931362784. Its totient is φ = 418766016.

The previous prime is 1221401009. The next prime is 1221401021. The reversal of 1221401020 is 201041221.

It is a happy number.

It is a super-3 number, since 3×1221401020³ (a number of 28 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221401021) 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, 4362007 + ... + 4362286.

It is an arithmetic number, because the mean of its divisors is an integer number (122140116).

Almost surely, 2^1221401020 is an apocalyptic number.

1221401020 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221401020 is an abundant number, since it is smaller than the sum of its proper divisors (1709961764).

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

1221401020 is a wasteful number, since it uses less digits than its factorization.

1221401020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8724309 (or 8724307 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 13.

The square root of 1221401020 is about 34948.5481815769. The cubic root of 1221401020 is about 1068.9385986832.

Adding to 1221401020 its reverse (201041221), we get a palindrome (1422442241).

The spelling of 1221401020 in words is "one billion, two hundred twenty-one million, four hundred one thousand, twenty".