21123400351 has 16 divisors (see below), whose sum is σ = 21655710720. Its totient is φ = 20598752160.

The previous prime is 21123400343. The next prime is 21123400373. The reversal of 21123400351 is 15300432112.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21123400351 - 2³ = 21123400343 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21123400321) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2729850 + ... + 2737576.

It is an arithmetic number, because the mean of its divisors is an integer number (1353481920).

Almost surely, 2^21123400351 is an apocalyptic number.

21123400351 is a deficient number, since it is larger than the sum of its proper divisors (532310369).

21123400351 is a wasteful number, since it uses less digits than its factorization.

21123400351 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8214.

The product of its (nonzero) digits is 720, while the sum is 22.

Adding to 21123400351 its reverse (15300432112), we get a palindrome (36423832463).

The spelling of 21123400351 in words is "twenty-one billion, one hundred twenty-three million, four hundred thousand, three hundred fifty-one".