1221501243420 has 72 divisors (see below), whose sum is σ = 3712956024960. Its totient is φ = 325053613440.

The previous prime is 1221501243407. The next prime is 1221501243439. The reversal of 1221501243420 is 243421051221.

1221501243420 is a `hidden beast` number, since 1 + 2 + 215 + 0 + 1 + 24 + 3 + 420 = 666.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 6997411 + ... + 7169850.

It is an arithmetic number, because the mean of its divisors is an integer number (51568833680).

Almost surely, 2^{1221501243420} is an apocalyptic number.

1221501243420 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221501243420 is an abundant number, since it is smaller than the sum of its proper divisors (2491454781540).

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

1221501243420 is a wasteful number, since it uses less digits than its factorization.

1221501243420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14167755 (or 14167750 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 27.

Adding to 1221501243420 its reverse (243421051221), we get a palindrome (1464922294641).

The spelling of 1221501243420 in words is "one trillion, two hundred twenty-one billion, five hundred one million, two hundred forty-three thousand, four hundred twenty".