1216821634 has 16 divisors (see below), whose sum is σ = 2130363648. Its totient is φ = 510399072.

The previous prime is 1216821547. The next prime is 1216821677. The reversal of 1216821634 is 4361286121.

It is a self number, because there is not a number n which added to its sum of digits gives 1216821634.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 923979 + ... + 925294.

It is an arithmetic number, because the mean of its divisors is an integer number (133147728).

Almost surely, 2^1216821634 is an apocalyptic number.

1216821634 is a gapful number since it is divisible by the number (14) formed by its first and last digit.

1216821634 is a deficient number, since it is larger than the sum of its proper divisors (913542014).

1216821634 is a wasteful number, since it uses less digits than its factorization.

1216821634 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1849329.

The product of its digits is 13824, while the sum is 34.

The square root of 1216821634 is about 34882.9705443788. The cubic root of 1216821634 is about 1067.6010055308.

The spelling of 1216821634 in words is "one billion, two hundred sixteen million, eight hundred twenty-one thousand, six hundred thirty-four".