21623393501 has 2 divisors, whose sum is σ = 21623393502. Its totient is φ = 21623393500.

The previous prime is 21623393461. The next prime is 21623393503. The reversal of 21623393501 is 10539332612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17975837476 + 3647556025 = 134074^2 + 60395^2 .

It is a cyclic number.

It is not a de Polignac number, because 21623393501 - 2¹⁸ = 21623131357 is a prime.

It is a super-2 number, since 2×21623393501² (a number of 21 digits) contains 22 as substring.

Together with 21623393503, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21623393503) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10811696750 + 10811696751.

It is an arithmetic number, because the mean of its divisors is an integer number (10811696751).

Almost surely, 2^21623393501 is an apocalyptic number.

It is an amenable number.

21623393501 is a deficient number, since it is larger than the sum of its proper divisors (1).

21623393501 is an equidigital number, since it uses as much as digits as its factorization.

21623393501 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 29160, while the sum is 35.

The spelling of 21623393501 in words is "twenty-one billion, six hundred twenty-three million, three hundred ninety-three thousand, five hundred one".