1220400551 has 2 divisors, whose sum is σ = 1220400552. Its totient is φ = 1220400550.

The previous prime is 1220400499. The next prime is 1220400569. The reversal of 1220400551 is 1550040221.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1220400551 - 2³⁰ = 146658727 is a prime.

It is a super-2 number, since 2×1220400551² = 2978755009762207202, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1220400151) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610200275 + 610200276.

It is an arithmetic number, because the mean of its divisors is an integer number (610200276).

Almost surely, 2^1220400551 is an apocalyptic number.

1220400551 is a deficient number, since it is larger than the sum of its proper divisors (1).

1220400551 is an equidigital number, since it uses as much as digits as its factorization.

1220400551 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 400, while the sum is 20.

The square root of 1220400551 is about 34934.2317934716. The cubic root of 1220400551 is about 1068.6466574221.

Adding to 1220400551 its reverse (1550040221), we get a palindrome (2770440772).

The spelling of 1220400551 in words is "one billion, two hundred twenty million, four hundred thousand, five hundred fifty-one".