1221401999 has 4 divisors (see below), whose sum is σ = 1223802120. Its totient is φ = 1219001880.

The previous prime is 1221401983. The next prime is 1221402029. The reversal of 1221401999 is 9991041221.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1221401999 - 2⁴ = 1221401983 is a prime.

It is a super-2 number, since 2×1221401999² = 2983645686322392002, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221404999) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1199297 + ... + 1200314.

It is an arithmetic number, because the mean of its divisors is an integer number (305950530).

Almost surely, 2^1221401999 is an apocalyptic number.

1221401999 is a deficient number, since it is larger than the sum of its proper divisors (2400121).

1221401999 is an equidigital number, since it uses as much as digits as its factorization.

1221401999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2400120.

The product of its (nonzero) digits is 11664, while the sum is 38.

The square root of 1221401999 is about 34948.5621878783. The cubic root of 1221401999 is about 1068.9388842816.

The spelling of 1221401999 in words is "one billion, two hundred twenty-one million, four hundred one thousand, nine hundred ninety-nine".