1221262691 has 16 divisors (see below), whose sum is σ = 1343485440. Its totient is φ = 1100947680.

The previous prime is 1221262687. The next prime is 1221262697. The reversal of 1221262691 is 1962621221.

It is a cyclic number.

It is not a de Polignac number, because 1221262691 - 2² = 1221262687 is a prime.

It is a super-2 number, since 2×1221262691² = 2982965120857122962, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1221262697) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 820550 + ... + 822036.

It is an arithmetic number, because the mean of its divisors is an integer number (83967840).

Almost surely, 2^1221262691 is an apocalyptic number.

1221262691 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1221262691 is a deficient number, since it is larger than the sum of its proper divisors (122222749).

1221262691 is a wasteful number, since it uses less digits than its factorization.

1221262691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2074.

The product of its digits is 5184, while the sum is 32.

The square root of 1221262691 is about 34946.5690876801. The cubic root of 1221262691 is about 1068.8982431714.

The spelling of 1221262691 in words is "one billion, two hundred twenty-one million, two hundred sixty-two thousand, six hundred ninety-one".