21355139 has 8 divisors (see below), whose sum is σ = 23046240. Its totient is φ = 19670976.

The previous prime is 21355121. The next prime is 21355151. The reversal of 21355139 is 93155312.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21355139 - 2¹⁶ = 21289603 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21355199) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5954 + ... + 8840.

It is an arithmetic number, because the mean of its divisors is an integer number (2880780).

Almost surely, 2^21355139 is an apocalyptic number.

21355139 is a deficient number, since it is larger than the sum of its proper divisors (1691101).

21355139 is a wasteful number, since it uses less digits than its factorization.

21355139 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3469.

The product of its digits is 4050, while the sum is 29.

The square root of 21355139 is about 4621.1620832860. The cubic root of 21355139 is about 277.4389725930.

The spelling of 21355139 in words is "twenty-one million, three hundred fifty-five thousand, one hundred thirty-nine".