1221605542 has 8 divisors (see below), whose sum is σ = 1881932976. Its totient is φ = 594294552.

The previous prime is 1221605521. The next prime is 1221605549. The reversal of 1221605542 is 2455061221.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×1221605542² = 2984640200490227528, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 1221605542.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221605549) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8254018 + ... + 8254165.

It is an arithmetic number, because the mean of its divisors is an integer number (235241622).

Almost surely, 2^1221605542 is an apocalyptic number.

1221605542 is a deficient number, since it is larger than the sum of its proper divisors (660327434).

1221605542 is a wasteful number, since it uses less digits than its factorization.

1221605542 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16508222.

The product of its (nonzero) digits is 4800, while the sum is 28.

The square root of 1221605542 is about 34951.4741033908. The cubic root of 1221605542 is about 1068.9982594757.

Adding to 1221605542 its reverse (2455061221), we get a palindrome (3676666763).

The spelling of 1221605542 in words is "one billion, two hundred twenty-one million, six hundred five thousand, five hundred forty-two".