1221021154 has 4 divisors (see below), whose sum is σ = 1831531734. Its totient is φ = 610510576.

The previous prime is 1221021119. The next prime is 1221021173. The reversal of 1221021154 is 4511201221.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 1047493225 + 173527929 = 32365^2 + 13173^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 305255287 + ... + 305255290.

Almost surely, 2^1221021154 is an apocalyptic number.

1221021154 is a deficient number, since it is larger than the sum of its proper divisors (610510580).

1221021154 is an equidigital number, since it uses as much as digits as its factorization.

1221021154 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 610510579.

The product of its (nonzero) digits is 160, while the sum is 19.

The square root of 1221021154 is about 34943.1131126006. The cubic root of 1221021154 is about 1068.8277708918.

Adding to 1221021154 its reverse (4511201221), we get a palindrome (5732222375).

It can be divided in two parts, 122102 and 1154, that added together give a triangular number (123256 = T₄₉₆).

The spelling of 1221021154 in words is "one billion, two hundred twenty-one million, twenty-one thousand, one hundred fifty-four".