21542351 has 2 divisors, whose sum is σ = 21542352. Its totient is φ = 21542350.

The previous prime is 21542341. The next prime is 21542357. The reversal of 21542351 is 15324512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21542351 - 2²² = 17348047 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21542357) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10771175 + 10771176.

It is an arithmetic number, because the mean of its divisors is an integer number (10771176).

Almost surely, 2^21542351 is an apocalyptic number.

21542351 is a deficient number, since it is larger than the sum of its proper divisors (1).

21542351 is an equidigital number, since it uses as much as digits as its factorization.

21542351 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1200, while the sum is 23.

The square root of 21542351 is about 4641.3738267888. The cubic root of 21542351 is about 278.2473472741.

Adding to 21542351 its reverse (15324512), we get a palindrome (36866863).

The spelling of 21542351 in words is "twenty-one million, five hundred forty-two thousand, three hundred fifty-one".