221894537 has 4 divisors (see below), whose sum is σ = 223308036. Its totient is φ = 220481040.

The previous prime is 221894509. The next prime is 221894539. The reversal of 221894537 is 735498122.

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 65869456 + 156025081 = 8116^2 + 12491^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221894537 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 221894494 and 221894503.

It is not an unprimeable number, because it can be changed into a prime (221894539) 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, 706514 + ... + 706827.

It is an arithmetic number, because the mean of its divisors is an integer number (55827009).

Almost surely, 2^221894537 is an apocalyptic number.

It is an amenable number.

221894537 is a deficient number, since it is larger than the sum of its proper divisors (1413499).

221894537 is a wasteful number, since it uses less digits than its factorization.

221894537 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1413498.

The product of its digits is 120960, while the sum is 41.

The square root of 221894537 is about 14896.1248987782. The cubic root of 221894537 is about 605.4089960362.

The spelling of 221894537 in words is "two hundred twenty-one million, eight hundred ninety-four thousand, five hundred thirty-seven".