215221451 has 4 divisors (see below), whose sum is σ = 216541992. Its totient is φ = 213900912.

The previous prime is 215221421. The next prime is 215221463. The reversal of 215221451 is 154122512.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-215221451 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (215221421) 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, 660026 + ... + 660351.

It is an arithmetic number, because the mean of its divisors is an integer number (54135498).

Almost surely, 2^215221451 is an apocalyptic number.

215221451 is a deficient number, since it is larger than the sum of its proper divisors (1320541).

215221451 is a wasteful number, since it uses less digits than its factorization.

215221451 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1320540.

The product of its digits is 800, while the sum is 23.

The square root of 215221451 is about 14670.4277715410. The cubic root of 215221451 is about 599.2782534476.

Adding to 215221451 its reverse (154122512), we get a palindrome (369343963).

The spelling of 215221451 in words is "two hundred fifteen million, two hundred twenty-one thousand, four hundred fifty-one".