21542245 has 8 divisors (see below), whose sum is σ = 26117784. Its totient is φ = 17055744.

The previous prime is 21542233. The next prime is 21542263. The reversal of 21542245 is 54224512.

21542245 = T₂₃₀ + T₂₃₁ + ... + T₅₂₀.

It can be written as a sum of positive squares in 4 ways, for example, as 3364 + 21538881 = 58^2 + 4641^2 .

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21542245 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 7 ways as a sum of consecutive naturals, for example, 21724 + ... + 22693.

It is an arithmetic number, because the mean of its divisors is an integer number (3264723).

Almost surely, 2^21542245 is an apocalyptic number.

It is an amenable number.

21542245 is a deficient number, since it is larger than the sum of its proper divisors (4575539).

21542245 is an equidigital number, since it uses as much as digits as its factorization.

21542245 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44519.

The product of its digits is 3200, while the sum is 25.

The square root of 21542245 is about 4641.3624077419. The cubic root of 21542245 is about 278.2468908976.

Adding to 21542245 its reverse (54224512), we get a palindrome (75766757).

The spelling of 21542245 in words is "twenty-one million, five hundred forty-two thousand, two hundred forty-five".