21240855 has 12 divisors (see below), whose sum is σ = 36817560. Its totient is φ = 11328432.

The previous prime is 21240833. The next prime is 21240881. The reversal of 21240855 is 55804212.

It is a happy number.

It is not a de Polignac number, because 21240855 - 2¹⁰ = 21239831 is a prime.

It is a super-2 number, since 2×21240855² = 902347842262050, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 235965 + ... + 236054.

It is an arithmetic number, because the mean of its divisors is an integer number (3068130).

Almost surely, 2^21240855 is an apocalyptic number.

21240855 is a deficient number, since it is larger than the sum of its proper divisors (15576705).

21240855 is a wasteful number, since it uses less digits than its factorization.

21240855 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 472030 (or 472027 counting only the distinct ones).

The product of its (nonzero) digits is 3200, while the sum is 27.

The square root of 21240855 is about 4608.7802073868. The cubic root of 21240855 is about 276.9431736662.

The spelling of 21240855 in words is "twenty-one million, two hundred forty thousand, eight hundred fifty-five".