1221551154 has 24 divisors (see below), whose sum is σ = 2785994640. Its totient is φ = 385752888.

The previous prime is 1221551153. The next prime is 1221551159. The reversal of 1221551154 is 4511551221.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (1221551153) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1785552 + ... + 1786235.

It is an arithmetic number, because the mean of its divisors is an integer number (116083110).

Almost surely, 2^1221551154 is an apocalyptic number.

1221551154 is an abundant number, since it is smaller than the sum of its proper divisors (1564443486).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1221551154 is a wasteful number, since it uses less digits than its factorization.

1221551154 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3571814 (or 3571811 counting only the distinct ones).

The product of its digits is 2000, while the sum is 27.

The square root of 1221551154 is about 34950.6960445711. The cubic root of 1221551154 is about 1068.9823946874.

The spelling of 1221551154 in words is "one billion, two hundred twenty-one million, five hundred fifty-one thousand, one hundred fifty-four".