21156455 has 4 divisors (see below), whose sum is σ = 25387752. Its totient is φ = 16925160.

The previous prime is 21156419. The next prime is 21156463. The reversal of 21156455 is 55465112.

It is a happy number.

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

It is not a de Polignac number, because 21156455 - 2⁶ = 21156391 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2115641 + ... + 2115650.

It is an arithmetic number, because the mean of its divisors is an integer number (6346938).

Almost surely, 2^21156455 is an apocalyptic number.

21156455 is a deficient number, since it is larger than the sum of its proper divisors (4231297).

21156455 is an equidigital number, since it uses as much as digits as its factorization.

21156455 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4231296.

The product of its digits is 6000, while the sum is 29.

The square root of 21156455 is about 4599.6146577730. The cubic root of 21156455 is about 276.5758778574.

The spelling of 21156455 in words is "twenty-one million, one hundred fifty-six thousand, four hundred fifty-five".