21455619 has 16 divisors (see below), whose sum is σ = 30419712. Its totient is φ = 13421408.

The previous prime is 21455593. The next prime is 21455639. The reversal of 21455619 is 91655412.

It is a cyclic number.

It is not a de Polignac number, because 21455619 - 2⁷ = 21455491 is a prime.

It is a super-2 number, since 2×21455619² = 920687173346322, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21455619.

It is not an unprimeable number, because it can be changed into a prime (21455639) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 724 + ... + 6590.

It is an arithmetic number, because the mean of its divisors is an integer number (1901232).

Almost surely, 2^21455619 is an apocalyptic number.

21455619 is a deficient number, since it is larger than the sum of its proper divisors (8964093).

21455619 is a wasteful number, since it uses less digits than its factorization.

21455619 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5946.

The product of its digits is 10800, while the sum is 33.

The square root of 21455619 is about 4632.0210491750. The cubic root of 21455619 is about 277.8734263263.

The spelling of 21455619 in words is "twenty-one million, four hundred fifty-five thousand, six hundred nineteen".