21555256 has 8 divisors (see below), whose sum is σ = 40416120. Its totient is φ = 10777624.

The previous prime is 21555223. The next prime is 21555263. The reversal of 21555256 is 65255512.

It is a tau number, because it is divible by the number of its divisors (8).

It is a super-2 number, since 2×21555256² = 929258122451072, 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 as a sum of consecutive naturals, namely, 1347196 + ... + 1347211.

It is an arithmetic number, because the mean of its divisors is an integer number (5052015).

Almost surely, 2^21555256 is an apocalyptic number.

It is an amenable number.

21555256 is a deficient number, since it is larger than the sum of its proper divisors (18860864).

21555256 is a wasteful number, since it uses less digits than its factorization.

21555256 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2694413 (or 2694409 counting only the distinct ones).

The product of its digits is 15000, while the sum is 31.

The square root of 21555256 is about 4642.7638320294. The cubic root of 21555256 is about 278.3028977760.

The spelling of 21555256 in words is "twenty-one million, five hundred fifty-five thousand, two hundred fifty-six".