21658138451 has 2 divisors, whose sum is σ = 21658138452. Its totient is φ = 21658138450.

The previous prime is 21658138423. The next prime is 21658138457. The reversal of 21658138451 is 15483185612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21658138451 - 2⁶ = 21658138387 is a prime.

It is a super-2 number, since 2×21658138451² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21658138457) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10829069225 + 10829069226.

It is an arithmetic number, because the mean of its divisors is an integer number (10829069226).

Almost surely, 2^21658138451 is an apocalyptic number.

21658138451 is a deficient number, since it is larger than the sum of its proper divisors (1).

21658138451 is an equidigital number, since it uses as much as digits as its factorization.

21658138451 is an evil number, because the sum of its binary digits is even.

The product of its digits is 230400, while the sum is 44.

The spelling of 21658138451 in words is "twenty-one billion, six hundred fifty-eight million, one hundred thirty-eight thousand, four hundred fifty-one".