1206651221 has 4 divisors (see below), whose sum is σ = 1270159200. Its totient is φ = 1143143244.

The previous prime is 1206651217. The next prime is 1206651239. The reversal of 1206651221 is 1221566021.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1221566021 = 13 ⋅93966617.

It is a cyclic number.

It is not a de Polignac number, because 1206651221 - 2² = 1206651217 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 (1206651521) 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, 31753961 + ... + 31753998.

It is an arithmetic number, because the mean of its divisors is an integer number (317539800).

Almost surely, 2^1206651221 is an apocalyptic number.

It is an amenable number.

1206651221 is a deficient number, since it is larger than the sum of its proper divisors (63507979).

1206651221 is an equidigital number, since it uses as much as digits as its factorization.

1206651221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63507978.

The product of its (nonzero) digits is 1440, while the sum is 26.

The square root of 1206651221 is about 34736.8855973013. The cubic root of 1206651221 is about 1064.6182798861.

The spelling of 1206651221 in words is "one billion, two hundred six million, six hundred fifty-one thousand, two hundred twenty-one".