61217215 has 4 divisors (see below), whose sum is σ = 73460664. Its totient is φ = 48973768.

The previous prime is 61217213. The next prime is 61217227. The reversal of 61217215 is 51271216.

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

It is a cyclic number.

It is not a de Polignac number, because 61217215 - 2¹ = 61217213 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 61217215.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61217213) 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, 6121717 + ... + 6121726.

It is an arithmetic number, because the mean of its divisors is an integer number (18365166).

Almost surely, 2^61217215 is an apocalyptic number.

61217215 is a deficient number, since it is larger than the sum of its proper divisors (12243449).

61217215 is a wasteful number, since it uses less digits than its factorization.

61217215 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12243448.

The product of its digits is 840, while the sum is 25.

The square root of 61217215 is about 7824.1430840700. The cubic root of 61217215 is about 394.1164141043.

The spelling of 61217215 in words is "sixty-one million, two hundred seventeen thousand, two hundred fifteen".