1221372644 has 12 divisors (see below), whose sum is σ = 2182879104. Its totient is φ = 597692904.

The previous prime is 1221372641. The next prime is 1221372679. The reversal of 1221372644 is 4462731221.

It is a super-2 number, since 2×1221372644² = 2983502271023101472, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 1221372644.

It is not an unprimeable number, because it can be changed into a prime (1221372641) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3248144 + ... + 3248519.

It is an arithmetic number, because the mean of its divisors is an integer number (181906592).

Almost surely, 2^1221372644 is an apocalyptic number.

It is an amenable number.

1221372644 is a deficient number, since it is larger than the sum of its proper divisors (961506460).

1221372644 is a wasteful number, since it uses less digits than its factorization.

1221372644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6496714 (or 6496712 counting only the distinct ones).

The product of its digits is 16128, while the sum is 32.

The square root of 1221372644 is about 34948.1422109960. The cubic root of 1221372644 is about 1068.9303206385.

The spelling of 1221372644 in words is "one billion, two hundred twenty-one million, three hundred seventy-two thousand, six hundred forty-four".