1226721920 has 32 divisors (see below), whose sum is σ = 2932633620. Its totient is φ = 490688512.

The previous prime is 1226721919. The next prime is 1226721929. The reversal of 1226721920 is 291276221.

It can be written as a sum of positive squares in 2 ways, for example, as 1157632576 + 69089344 = 34024^2 + 8312^2 .

It is a tau number, because it is divible by the number of its divisors (32).

It is a Harshad number since it is a multiple of its sum of digits (32).

It is not an unprimeable number, because it can be changed into a prime (1226721929) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 957737 + ... + 959016.

Almost surely, 2^1226721920 is an apocalyptic number.

1226721920 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1226721920 is an abundant number, since it is smaller than the sum of its proper divisors (1705911700).

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

1226721920 is an equidigital number, since it uses as much as digits as its factorization.

1226721920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1916772 (or 1916760 counting only the distinct ones).

The product of its (nonzero) digits is 6048, while the sum is 32.

The square root of 1226721920 is about 35024.5902188734. The cubic root of 1226721920 is about 1070.4885881147.

The spelling of 1226721920 in words is "one billion, two hundred twenty-six million, seven hundred twenty-one thousand, nine hundred twenty".