1221066651 has 16 divisors (see below), whose sum is σ = 1867547648. Its totient is φ = 695174400.

The previous prime is 1221066643. The next prime is 1221066677. The reversal of 1221066651 is 1566601221.

It is not a de Polignac number, because 1221066651 - 2³ = 1221066643 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1221066641) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 101590 + ... + 112971.

It is an arithmetic number, because the mean of its divisors is an integer number (116721728).

Almost surely, 2^1221066651 is an apocalyptic number.

1221066651 is a deficient number, since it is larger than the sum of its proper divisors (646480997).

1221066651 is a wasteful number, since it uses less digits than its factorization.

1221066651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 214842.

The product of its (nonzero) digits is 4320, while the sum is 30.

The square root of 1221066651 is about 34943.7641218000. The cubic root of 1221066651 is about 1068.8410460790.

Adding to 1221066651 its reverse (1566601221), we get a palindrome (2787667872).

The spelling of 1221066651 in words is "one billion, two hundred twenty-one million, sixty-six thousand, six hundred fifty-one".