126781711921 has 4 divisors (see below), whose sum is σ = 128012602432. Its totient is φ = 125550821412.

The previous prime is 126781711879. The next prime is 126781711949. The reversal of 126781711921 is 129117187621.

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: 129117187621 = 499 ⋅258751879.

It is a cyclic number.

It is not a de Polignac number, because 126781711921 - 2⁹ = 126781711409 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (126781712921) 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, 615445101 + ... + 615445306.

It is an arithmetic number, because the mean of its divisors is an integer number (32003150608).

Almost surely, 2^126781711921 is an apocalyptic number.

It is an amenable number.

126781711921 is a deficient number, since it is larger than the sum of its proper divisors (1230890511).

126781711921 is a wasteful number, since it uses less digits than its factorization.

126781711921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1230890510.

The product of its digits is 84672, while the sum is 46.

The spelling of 126781711921 in words is "one hundred twenty-six billion, seven hundred eighty-one million, seven hundred eleven thousand, nine hundred twenty-one".