1212721406 has 32 divisors (see below), whose sum is σ = 1992402048. Its totient is φ = 550229760.

The previous prime is 1212721403. The next prime is 1212721409. The reversal of 1212721406 is 6041272121.

It is an interprime number because it is at equal distance from previous prime (1212721403) and next prime (1212721409).

It is a Harshad number since it is a multiple of its sum of digits (26).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1212721403) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 695696 + ... + 697436.

It is an arithmetic number, because the mean of its divisors is an integer number (62262564).

Almost surely, 2^1212721406 is an apocalyptic number.

1212721406 is a deficient number, since it is larger than the sum of its proper divisors (779680642).

1212721406 is a wasteful number, since it uses less digits than its factorization.

1212721406 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2196.

The product of its (nonzero) digits is 1344, while the sum is 26.

The square root of 1212721406 is about 34824.1497527219. The cubic root of 1212721406 is about 1066.4005191233.

Adding to 1212721406 its reverse (6041272121), we get a palindrome (7253993527).

It can be divided in two parts, 12127 and 21406, that added together give a palindrome (33533).

The spelling of 1212721406 in words is "one billion, two hundred twelve million, seven hundred twenty-one thousand, four hundred six".