1240020421 has 4 divisors (see below), whose sum is σ = 1240092000. Its totient is φ = 1239948844.

The previous prime is 1240020407. The next prime is 1240020437. The reversal of 1240020421 is 1240200421.

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, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 1240200421 = 47 ⋅26387243.

It is a cyclic number.

It is not a de Polignac number, because 1240020421 - 2⁷ = 1240020293 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1240020395 and 1240020404.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1240020401) 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, 8310 + ... + 50488.

It is an arithmetic number, because the mean of its divisors is an integer number (310023000).

Almost surely, 2^1240020421 is an apocalyptic number.

It is an amenable number.

1240020421 is a deficient number, since it is larger than the sum of its proper divisors (71579).

1240020421 is an equidigital number, since it uses as much as digits as its factorization.

1240020421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71578.

The product of its (nonzero) digits is 128, while the sum is 16.

The square root of 1240020421 is about 35213.9236808397. The cubic root of 1240020421 is about 1074.3429685473.

Adding to 1240020421 its reverse (1240200421), we get a palindrome (2480220842).

The spelling of 1240020421 in words is "one billion, two hundred forty million, twenty thousand, four hundred twenty-one".