1221266731 has 8 divisors (see below), whose sum is σ = 1275853824. Its totient is φ = 1167629160.

The previous prime is 1221266699. The next prime is 1221266737. The reversal of 1221266731 is 1376621221.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1221266731 - 2⁵ = 1221266699 is a prime.

It is a super-2 number, since 2×1221266731² = 2982984856494852722, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1221266693 and 1221266702.

It is not an unprimeable number, because it can be changed into a prime (1221266737) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 234751 + ... + 239896.

It is an arithmetic number, because the mean of its divisors is an integer number (159481728).

Almost surely, 2^1221266731 is an apocalyptic number.

1221266731 is a deficient number, since it is larger than the sum of its proper divisors (54587093).

1221266731 is an equidigital number, since it uses as much as digits as its factorization.

1221266731 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 474761.

The product of its digits is 6048, while the sum is 31.

The square root of 1221266731 is about 34946.6268901592. The cubic root of 1221266731 is about 1068.8994218269.

Adding to 1221266731 its reverse (1376621221), we get a palindrome (2597887952).

The spelling of 1221266731 in words is "one billion, two hundred twenty-one million, two hundred sixty-six thousand, seven hundred thirty-one".