1221420451 has 16 divisors (see below), whose sum is σ = 1300202496. Its totient is φ = 1144984896.

The previous prime is 1221420449. The next prime is 1221420469. The reversal of 1221420451 is 1540241221.

It is not a de Polignac number, because 1221420451 - 2¹ = 1221420449 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1221421451) 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, 271446 + ... + 275908.

It is an arithmetic number, because the mean of its divisors is an integer number (81262656).

Almost surely, 2^1221420451 is an apocalyptic number.

1221420451 is a deficient number, since it is larger than the sum of its proper divisors (78782045).

1221420451 is a wasteful number, since it uses less digits than its factorization.

1221420451 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4722.

The product of its (nonzero) digits is 640, while the sum is 22.

The square root of 1221420451 is about 34948.8261748517. The cubic root of 1221420451 is about 1068.9442671561.

Adding to 1221420451 its reverse (1540241221), we get a palindrome (2761661672).

The spelling of 1221420451 in words is "one billion, two hundred twenty-one million, four hundred twenty thousand, four hundred fifty-one".