1220531621 has 2 divisors, whose sum is σ = 1220531622. Its totient is φ = 1220531620.

The previous prime is 1220531567. The next prime is 1220531657. The reversal of 1220531621 is 1261350221.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 917423521 + 303108100 = 30289^2 + 17410^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1220531621 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1220531681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610265810 + 610265811.

It is an arithmetic number, because the mean of its divisors is an integer number (610265811).

Almost surely, 2^1220531621 is an apocalyptic number.

It is an amenable number.

1220531621 is a deficient number, since it is larger than the sum of its proper divisors (1).

1220531621 is an equidigital number, since it uses as much as digits as its factorization.

1220531621 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 720, while the sum is 23.

The square root of 1220531621 is about 34936.1076967655. The cubic root of 1220531621 is about 1068.6849133054.

Adding to 1220531621 its reverse (1261350221), we get a palindrome (2481881842).

The spelling of 1220531621 in words is "one billion, two hundred twenty million, five hundred thirty-one thousand, six hundred twenty-one".