1220991615 has 72 divisors (see below), whose sum is σ = 2205504288. Its totient is φ = 624731520.

The previous prime is 1220991613. The next prime is 1220991617. The reversal of 1220991615 is 5161990221.

1220991615 is a `hidden beast` number, since 12 + 20 + 9 + 9 + 1 + 615 = 666.

It is an interprime number because it is at equal distance from previous prime (1220991613) and next prime (1220991617).

It is not a de Polignac number, because 1220991615 - 2¹ = 1220991613 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1220991615.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1220991613) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 7057669 + ... + 7057841.

It is an arithmetic number, because the mean of its divisors is an integer number (30632004).

Almost surely, 2^1220991615 is an apocalyptic number.

1220991615 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

1220991615 is a deficient number, since it is larger than the sum of its proper divisors (984512673).

1220991615 is a wasteful number, since it uses less digits than its factorization.

1220991615 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 349 (or 299 counting only the distinct ones).

The product of its (nonzero) digits is 9720, while the sum is 36.

The square root of 1220991615 is about 34942.6904373433. The cubic root of 1220991615 is about 1068.8191517788.

The spelling of 1220991615 in words is "one billion, two hundred twenty million, nine hundred ninety-one thousand, six hundred fifteen".