1221402021 has 32 divisors (see below), whose sum is σ = 1896652800. Its totient is φ = 684761664.

The previous prime is 1221401983. The next prime is 1221402029. The reversal of 1221402021 is 1202041221.

It is not a de Polignac number, because 1221402021 - 2²⁵ = 1187847589 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221402029) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 257356 + ... + 262058.

It is an arithmetic number, because the mean of its divisors is an integer number (59270400).

Almost surely, 2^1221402021 is an apocalyptic number.

It is an amenable number.

1221402021 is a deficient number, since it is larger than the sum of its proper divisors (675250779).

1221402021 is a wasteful number, since it uses less digits than its factorization.

1221402021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4945.

The product of its (nonzero) digits is 64, while the sum is 15.

The square root of 1221402021 is about 34948.5625026266. The cubic root of 1221402021 is about 1068.9388906996.

Adding to 1221402021 its reverse (1202041221), we get a palindrome (2423443242).

The spelling of 1221402021 in words is "one billion, two hundred twenty-one million, four hundred two thousand, twenty-one".