1221631 has 2 divisors, whose sum is σ = 1221632. Its totient is φ = 1221630.

The previous prime is 1221601. The next prime is 1221641. The reversal of 1221631 is 1361221.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1221631 - 2⁷ = 1221503 is a prime.

It is a super-2 number, since 2×1221631² = 2984764600322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1221601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610815 + 610816.

It is an arithmetic number, because the mean of its divisors is an integer number (610816).

2^1221631 is an apocalyptic number.

1221631 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221631 is an equidigital number, since it uses as much as digits as its factorization.

1221631 is an evil number, because the sum of its binary digits is even.

The product of its digits is 72, while the sum is 16.

The square root of 1221631 is about 1105.2741741306. The cubic root of 1221631 is about 106.9005685323.

Adding to 1221631 its reverse (1361221), we get a palindrome (2582852).

The spelling of 1221631 in words is "one million, two hundred twenty-one thousand, six hundred thirty-one".