1221882781 has 16 divisors (see below), whose sum is σ = 1449763200. Its totient is φ = 1007592768.

The previous prime is 1221882731. The next prime is 1221882787. The reversal of 1221882781 is 1872881221.

It is not a de Polignac number, because 1221882781 - 2⁷ = 1221882653 is a prime.

It is a super-2 number, since 2×1221882781² = 2985995061008587922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221882787) 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, 46815 + ... + 68083.

It is an arithmetic number, because the mean of its divisors is an integer number (90610200).

Almost surely, 2^1221882781 is an apocalyptic number.

It is an amenable number.

1221882781 is a deficient number, since it is larger than the sum of its proper divisors (227880419).

1221882781 is a wasteful number, since it uses less digits than its factorization.

1221882781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21588.

The product of its digits is 28672, while the sum is 40.

The square root of 1221882781 is about 34955.4399342935. The cubic root of 1221882781 is about 1069.0791218003.

The spelling of 1221882781 in words is "one billion, two hundred twenty-one million, eight hundred eighty-two thousand, seven hundred eighty-one".