21123401455 has 32 divisors (see below), whose sum is σ = 27573436800. Its totient is φ = 15442106880.

The previous prime is 21123401423. The next prime is 21123401461. The reversal of 21123401455 is 55410432112.

It is not a de Polignac number, because 21123401455 - 2⁵ = 21123401423 is a prime.

It is a super-2 number, since 2×21123401455² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3008529 + ... + 3015541.

It is an arithmetic number, because the mean of its divisors is an integer number (861669900).

Almost surely, 2^21123401455 is an apocalyptic number.

21123401455 is a deficient number, since it is larger than the sum of its proper divisors (6450035345).

21123401455 is a wasteful number, since it uses less digits than its factorization.

21123401455 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7491.

The product of its (nonzero) digits is 4800, while the sum is 28.

Adding to 21123401455 its reverse (55410432112), we get a palindrome (76533833567).

The spelling of 21123401455 in words is "twenty-one billion, one hundred twenty-three million, four hundred one thousand, four hundred fifty-five".