21426905 has 4 divisors (see below), whose sum is σ = 25712292. Its totient is φ = 17141520.

The previous prime is 21426901. The next prime is 21426907. The reversal of 21426905 is 50962412.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 13564489 + 7862416 = 3683^2 + 2804^2 .

It is not a de Polignac number, because 21426905 - 2² = 21426901 is a prime.

It is a super-2 number, since 2×21426905² = 918224515758050, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21426901) 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, 2142686 + ... + 2142695.

It is an arithmetic number, because the mean of its divisors is an integer number (6428073).

Almost surely, 2^21426905 is an apocalyptic number.

It is an amenable number.

21426905 is a deficient number, since it is larger than the sum of its proper divisors (4285387).

21426905 is an equidigital number, since it uses as much as digits as its factorization.

21426905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4285386.

The product of its (nonzero) digits is 4320, while the sum is 29.

The square root of 21426905 is about 4628.9205005055. The cubic root of 21426905 is about 277.7494118886.

The spelling of 21426905 in words is "twenty-one million, four hundred twenty-six thousand, nine hundred five".