421251315221561 has 4 divisors (see below), whose sum is σ = 459546889332624. Its totient is φ = 382955741110500.

The previous prime is 421251315221549. The next prime is 421251315221567. The reversal of 421251315221561 is 165122513152124.

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 421251315221561 - 2²⁶ = 421251248112697 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (421251315221567) 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, 19147787055515 + ... + 19147787055536.

It is an arithmetic number, because the mean of its divisors is an integer number (114886722333156).

Almost surely, 2^{421251315221561} is an apocalyptic number.

It is an amenable number.

421251315221561 is a deficient number, since it is larger than the sum of its proper divisors (38295574111063).

421251315221561 is a wasteful number, since it uses less digits than its factorization.

421251315221561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38295574111062.

The product of its digits is 144000, while the sum is 41.

Adding to 421251315221561 its reverse (165122513152124), we get a palindrome (586373828373685).

The spelling of 421251315221561 in words is "four hundred twenty-one trillion, two hundred fifty-one billion, three hundred fifteen million, two hundred twenty-one thousand, five hundred sixty-one".