1221390740 has 24 divisors (see below), whose sum is σ = 2600059560. Its totient is φ = 481863168.

The previous prime is 1221390719. The next prime is 1221390749. The reversal of 1221390740 is 470931221.

It can be written as a sum of positive squares in 4 ways, for example, as 354794896 + 866595844 = 18836^2 + 29438^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221390749) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 416825 + ... + 419744.

It is an arithmetic number, because the mean of its divisors is an integer number (108335815).

Almost surely, 2^1221390740 is an apocalyptic number.

1221390740 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221390740 is an abundant number, since it is smaller than the sum of its proper divisors (1378668820).

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

1221390740 is a wasteful number, since it uses less digits than its factorization.

1221390740 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 836651 (or 836649 counting only the distinct ones).

The product of its (nonzero) digits is 3024, while the sum is 29.

The square root of 1221390740 is about 34948.4011079191. The cubic root of 1221390740 is about 1068.9355997447.

The spelling of 1221390740 in words is "one billion, two hundred twenty-one million, three hundred ninety thousand, seven hundred forty".