1221400121 has 8 divisors (see below), whose sum is σ = 1226495304. Its totient is φ = 1216314880.

The previous prime is 1221400097. The next prime is 1221400153. The reversal of 1221400121 is 1210041221.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 351150121 + 870250000 = 18739^2 + 29500^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1221400121 - 2¹⁸ = 1221137977 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1221400096 and 1221400105.

It is not an unprimeable number, because it can be changed into a prime (1221400721) 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, 330335 + ... + 334011.

It is an arithmetic number, because the mean of its divisors is an integer number (153311913).

Almost surely, 2^1221400121 is an apocalyptic number.

It is an amenable number.

1221400121 is a deficient number, since it is larger than the sum of its proper divisors (5095183).

1221400121 is an equidigital number, since it uses as much as digits as its factorization.

1221400121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4971.

The product of its (nonzero) digits is 32, while the sum is 14.

The square root of 1221400121 is about 34948.5353198099. The cubic root of 1221400121 is about 1068.9383364226.

Adding to 1221400121 its reverse (1210041221), we get a palindrome (2431441342).

The spelling of 1221400121 in words is "one billion, two hundred twenty-one million, four hundred thousand, one hundred twenty-one".