1221006404 has 12 divisors (see below), whose sum is σ = 2188877628. Its totient is φ = 595612800.

The previous prime is 1221006379. The next prime is 1221006463. The reversal of 1221006404 is 4046001221.

It can be written as a sum of positive squares in 2 ways, for example, as 321126400 + 899880004 = 17920^2 + 29998^2 .

It is a super-2 number, since 2×1221006404² = 2981713277218022432, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3722417 + ... + 3722744.

It is an arithmetic number, because the mean of its divisors is an integer number (182406469).

Almost surely, 2^1221006404 is an apocalyptic number.

It is an amenable number.

1221006404 is a deficient number, since it is larger than the sum of its proper divisors (967871224).

1221006404 is a wasteful number, since it uses less digits than its factorization.

1221006404 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7445206 (or 7445204 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 20.

The square root of 1221006404 is about 34942.9020546376. The cubic root of 1221006404 is about 1068.8234670425.

Adding to 1221006404 its reverse (4046001221), we get a palindrome (5267007625).

The spelling of 1221006404 in words is "one billion, two hundred twenty-one million, six thousand, four hundred four".