1256221998 has 24 divisors (see below), whose sum is σ = 2739156888. Its totient is φ = 416072592.

The previous prime is 1256221991. The next prime is 1256222053. The reversal of 1256221998 is 8991226521.

It is a happy number.

1256221998 is a `hidden beast` number, since 1 + 2 + 5 + 622 + 19 + 9 + 8 = 666.

It is a super-2 number, since 2×1256221998² = 3156187416518224008, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1256221991) 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, 219436 + ... + 225087.

It is an arithmetic number, because the mean of its divisors is an integer number (114131537).

Almost surely, 2^1256221998 is an apocalyptic number.

1256221998 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

1256221998 is an abundant number, since it is smaller than the sum of its proper divisors (1482934890).

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

1256221998 is a wasteful number, since it uses less digits than its factorization.

1256221998 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 444688 (or 444685 counting only the distinct ones).

The product of its digits is 155520, while the sum is 45.

The square root of 1256221998 is about 35443.2221729346. Note that the first 3 decimals coincide. The cubic root of 1256221998 is about 1079.0017061160.

The spelling of 1256221998 in words is "one billion, two hundred fifty-six million, two hundred twenty-one thousand, nine hundred ninety-eight".