21123401457 has 32 divisors (see below), whose sum is σ = 30367457280. Its totient is φ = 13022444160.

The previous prime is 21123401423. The next prime is 21123401461. The reversal of 21123401457 is 75410432112.

It is not a de Polignac number, because 21123401457 - 2¹⁵ = 21123368689 is a prime.

It is a super-2 number, since 2×21123401457² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21123408457) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2410558 + ... + 2419304.

It is an arithmetic number, because the mean of its divisors is an integer number (948983040).

Almost surely, 2^21123401457 is an apocalyptic number.

It is an amenable number.

21123401457 is a deficient number, since it is larger than the sum of its proper divisors (9244055823).

21123401457 is a wasteful number, since it uses less digits than its factorization.

21123401457 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9933.

The product of its (nonzero) digits is 6720, while the sum is 30.

Adding to 21123401457 its reverse (75410432112), we get a palindrome (96533833569).

The spelling of 21123401457 in words is "twenty-one billion, one hundred twenty-three million, four hundred one thousand, four hundred fifty-seven".