1217020421 has 4 divisors (see below), whose sum is σ = 1217541312. Its totient is φ = 1216499532.

The previous prime is 1217020403. The next prime is 1217020447. The reversal of 1217020421 is 1240207121.

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 a de Polignac number, because none of the positive numbers 2^k-1217020421 is a prime.

It is a super-2 number, since 2×1217020421² = 2962277410262034482, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1217020393 and 1217020402.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1217020921) 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, 256925 + ... + 261618.

It is an arithmetic number, because the mean of its divisors is an integer number (304385328).

Almost surely, 2^1217020421 is an apocalyptic number.

It is an amenable number.

1217020421 is a deficient number, since it is larger than the sum of its proper divisors (520891).

1217020421 is an equidigital number, since it uses as much as digits as its factorization.

1217020421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 520890.

The product of its (nonzero) digits is 224, while the sum is 20.

The square root of 1217020421 is about 34885.8197696428. The cubic root of 1217020421 is about 1067.6591388511.

Adding to 1217020421 its reverse (1240207121), we get a palindrome (2457227542).

The spelling of 1217020421 in words is "one billion, two hundred seventeen million, twenty thousand, four hundred twenty-one".