1216561210 has 32 divisors (see below), whose sum is σ = 2294226432. Its totient is φ = 463890240.

The previous prime is 1216561193. The next prime is 1216561253. The reversal of 1216561210 is 121656121.

It is a happy number.

It is an alternating number because its digits alternate between odd and even.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8517 + ... + 50056.

It is an arithmetic number, because the mean of its divisors is an integer number (71694576).

Almost surely, 2^1216561210 is an apocalyptic number.

1216561210 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1216561210 is a deficient number, since it is larger than the sum of its proper divisors (1077665222).

1216561210 is a wasteful number, since it uses less digits than its factorization.

1216561210 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58678.

The product of its (nonzero) digits is 720, while the sum is 25.

The square root of 1216561210 is about 34879.2375203358. The cubic root of 1216561210 is about 1067.5248374896.

The spelling of 1216561210 in words is "one billion, two hundred sixteen million, five hundred sixty-one thousand, two hundred ten".