1209901221 has 12 divisors (see below), whose sum is σ = 1794868972. Its totient is φ = 784800576.

The previous prime is 1209901211. The next prime is 1209901243. The reversal of 1209901221 is 1221099021.

It can be written as a sum of positive squares in 2 ways, for example, as 610337025 + 599564196 = 24705^2 + 24486^2 .

It is not a de Polignac number, because 1209901221 - 2⁷ = 1209901093 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1209901211) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1816336 + ... + 1817001.

Almost surely, 2^1209901221 is an apocalyptic number.

It is an amenable number.

1209901221 is a deficient number, since it is larger than the sum of its proper divisors (584967751).

1209901221 is a wasteful number, since it uses less digits than its factorization.

1209901221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3633380 (or 3633377 counting only the distinct ones).

The product of its (nonzero) digits is 648, while the sum is 27.

The square root of 1209901221 is about 34783.6343845780. The cubic root of 1209901221 is about 1065.5732389738.

The spelling of 1209901221 in words is "one billion, two hundred nine million, nine hundred one thousand, two hundred twenty-one".