1221145005 has 32 divisors (see below), whose sum is σ = 1975025664. Its totient is φ = 644245056.

The previous prime is 1221144989. The next prime is 1221145043. The reversal of 1221145005 is 5005411221.

It is not a de Polignac number, because 1221145005 - 2⁴ = 1221144989 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 843192 + ... + 844638.

It is an arithmetic number, because the mean of its divisors is an integer number (61719552).

Almost surely, 2^1221145005 is an apocalyptic number.

1221145005 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1221145005 is a deficient number, since it is larger than the sum of its proper divisors (753880659).

1221145005 is a wasteful number, since it uses less digits than its factorization.

1221145005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2025.

The product of its (nonzero) digits is 400, while the sum is 21.

The square root of 1221145005 is about 34944.8852480588. The cubic root of 1221145005 is about 1068.8639075611.

Adding to 1221145005 its reverse (5005411221), we get a palindrome (6226556226).

The spelling of 1221145005 in words is "one billion, two hundred twenty-one million, one hundred forty-five thousand, five".