21423501551 has 2 divisors, whose sum is σ = 21423501552. Its totient is φ = 21423501550.

The previous prime is 21423501521. The next prime is 21423501559. The reversal of 21423501551 is 15510532412.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21423501551 - 2⁶ = 21423501487 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21423501559) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10711750775 + 10711750776.

It is an arithmetic number, because the mean of its divisors is an integer number (10711750776).

Almost surely, 2^21423501551 is an apocalyptic number.

21423501551 is a deficient number, since it is larger than the sum of its proper divisors (1).

21423501551 is an equidigital number, since it uses as much as digits as its factorization.

21423501551 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6000, while the sum is 29.

The spelling of 21423501551 in words is "twenty-one billion, four hundred twenty-three million, five hundred one thousand, five hundred fifty-one".