1421771781 has 4 divisors (see below), whose sum is σ = 1895695712. Its totient is φ = 947847852.

The previous prime is 1421771779. The next prime is 1421771797. The reversal of 1421771781 is 1871771241.

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 an emirpimes, since its reverse is a distinct semiprime: 1871771241 = 3 ⋅623923747.

It is not a de Polignac number, because 1421771781 - 2¹ = 1421771779 is a prime.

It is a super-2 number, since 2×1421771781² = 4042869994495823922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1421771711) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 236961961 + ... + 236961966.

It is an arithmetic number, because the mean of its divisors is an integer number (473923928).

Almost surely, 2^1421771781 is an apocalyptic number.

It is an amenable number.

1421771781 is a deficient number, since it is larger than the sum of its proper divisors (473923931).

1421771781 is an equidigital number, since it uses as much as digits as its factorization.

1421771781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 473923930.

The product of its digits is 21952, while the sum is 39.

The square root of 1421771781 is about 37706.3891270432. The cubic root of 1421771781 is about 1124.4581505201.

The spelling of 1421771781 in words is "one billion, four hundred twenty-one million, seven hundred seventy-one thousand, seven hundred eighty-one".