1225543891 has 24 divisors (see below), whose sum is σ = 1510707456. Its totient is φ = 983679840.

The previous prime is 1225543861. The next prime is 1225543939. The reversal of 1225543891 is 1983455221.

It is a happy number.

It is not a de Polignac number, because 1225543891 - 2¹³ = 1225535699 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1225543861) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 28426 + ... + 57088.

It is an arithmetic number, because the mean of its divisors is an integer number (62946144).

Almost surely, 2^1225543891 is an apocalyptic number.

1225543891 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1225543891 is a deficient number, since it is larger than the sum of its proper divisors (285163565).

1225543891 is a wasteful number, since it uses less digits than its factorization.

1225543891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28723 (or 28710 counting only the distinct ones).

The product of its digits is 86400, while the sum is 40.

The square root of 1225543891 is about 35007.7690091785. The cubic root of 1225543891 is about 1070.1458126614.

The spelling of 1225543891 in words is "one billion, two hundred twenty-five million, five hundred forty-three thousand, eight hundred ninety-one".