123721919 has 4 divisors (see below), whose sum is σ = 123745944. Its totient is φ = 123697896.

The previous prime is 123721891. The next prime is 123721931. The reversal of 123721919 is 919127321.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 123721919 - 2¹⁶ = 123656383 is a prime.

It is a super-2 number, since 2×123721919² = 30614226482085122, 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 (123721519) 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, 797 + ... + 15750.

It is an arithmetic number, because the mean of its divisors is an integer number (30936486).

Almost surely, 2^123721919 is an apocalyptic number.

123721919 is a deficient number, since it is larger than the sum of its proper divisors (24025).

123721919 is an equidigital number, since it uses as much as digits as its factorization.

123721919 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24024.

The product of its digits is 6804, while the sum is 35.

The square root of 123721919 is about 11123.0355119455. The cubic root of 123721919 is about 498.2900508139.

The spelling of 123721919 in words is "one hundred twenty-three million, seven hundred twenty-one thousand, nine hundred nineteen".