21123401456 has 10 divisors (see below), whose sum is σ = 40926590352. Its totient is φ = 10561700720.

The previous prime is 21123401423. The next prime is 21123401461. The reversal of 21123401456 is 65410432112.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 660106280 + ... + 660106311.

Almost surely, 2^21123401456 is an apocalyptic number.

It is an amenable number.

21123401456 is a deficient number, since it is larger than the sum of its proper divisors (19803188896).

21123401456 is a wasteful number, since it uses less digits than its factorization.

21123401456 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1320212599 (or 1320212593 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 29.

Adding to 21123401456 its reverse (65410432112), we get a palindrome (86533833568).

The spelling of 21123401456 in words is "twenty-one billion, one hundred twenty-three million, four hundred one thousand, four hundred fifty-six".