21542907 has 4 divisors (see below), whose sum is σ = 28723880. Its totient is φ = 14361936.

The previous prime is 21542897. The next prime is 21542921. The reversal of 21542907 is 70924512.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21542907 - 2¹¹ = 21540859 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21542977) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3590482 + ... + 3590487.

It is an arithmetic number, because the mean of its divisors is an integer number (7180970).

Almost surely, 2^21542907 is an apocalyptic number.

21542907 is a deficient number, since it is larger than the sum of its proper divisors (7180973).

21542907 is an equidigital number, since it uses as much as digits as its factorization.

21542907 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7180972.

The product of its (nonzero) digits is 5040, while the sum is 30.

The square root of 21542907 is about 4641.4337224612. The cubic root of 21542907 is about 278.2497410734.

The spelling of 21542907 in words is "twenty-one million, five hundred forty-two thousand, nine hundred seven".