1242521621 has 4 divisors (see below), whose sum is σ = 1355478144. Its totient is φ = 1129565100.

The previous prime is 1242521611. The next prime is 1242521647. The reversal of 1242521621 is 1261252421.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1242521621 - 2²⁶ = 1175412757 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1242521611) 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, 56478245 + ... + 56478266.

It is an arithmetic number, because the mean of its divisors is an integer number (338869536).

Almost surely, 2^1242521621 is an apocalyptic number.

1242521621 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1242521621 is a deficient number, since it is larger than the sum of its proper divisors (112956523).

1242521621 is a wasteful number, since it uses less digits than its factorization.

1242521621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 112956522.

The product of its digits is 1920, while the sum is 26.

The square root of 1242521621 is about 35249.4201512592. The cubic root of 1242521621 is about 1075.0648227722.

The spelling of 1242521621 in words is "one billion, two hundred forty-two million, five hundred twenty-one thousand, six hundred twenty-one".