421756991578729 has 9 divisors (see below), whose sum is σ = 440892018052759. Its totient is φ = 403419279267400.

The previous prime is 421756991578673. The next prime is 421756991578753. The reversal of 421756991578729 is 927875199657124.

It is a happy number.

The square root of 421756991578729 is 20536723.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 60990273879129 + 360766717699600 = 7809627^2 + 18993860^2 .

It is a de Polignac number, because none of the positive numbers 2^k-421756991578729 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (421756991578759) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 471898179 + ... + 472791079.

Almost surely, 2^{421756991578729} is an apocalyptic number.

421756991578729 is the 20536723-rd square number.

421756991578729 is the 10268362-nd centered octagonal number.

It is an amenable number.

421756991578729 is a deficient number, since it is larger than the sum of its proper divisors (19135026474030).

421756991578729 is an frugal number, since it uses more digits than its factorization.

421756991578729 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1785848 (or 892924 counting only the distinct ones).

The product of its digits is 4800902400, while the sum is 82.

The spelling of 421756991578729 in words is "four hundred twenty-one trillion, seven hundred fifty-six billion, nine hundred ninety-one million, five hundred seventy-eight thousand, seven hundred twenty-nine".