123656167021 has 4 divisors (see below), whose sum is σ = 123658166044. Its totient is φ = 123654168000.

The previous prime is 123656166967. The next prime is 123656167051. The reversal of 123656167021 is 120761656321.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 120761656321 = 47 ⋅2569396943.

It can be written as a sum of positive squares in 2 ways, for example, as 101219422500 + 22436744521 = 318150^2 + 149789^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-123656167021 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (123656167051) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 903660 + ... + 1031461.

It is an arithmetic number, because the mean of its divisors is an integer number (30914541511).

Almost surely, 2^123656167021 is an apocalyptic number.

It is an amenable number.

123656167021 is a deficient number, since it is larger than the sum of its proper divisors (1999023).

123656167021 is an equidigital number, since it uses as much as digits as its factorization.

123656167021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1999022.

The product of its (nonzero) digits is 90720, while the sum is 40.

The spelling of 123656167021 in words is "one hundred twenty-three billion, six hundred fifty-six million, one hundred sixty-seven thousand, twenty-one".