1220021987 has 2 divisors, whose sum is σ = 1220021988. Its totient is φ = 1220021986.

The previous prime is 1220021969. The next prime is 1220021989. The reversal of 1220021987 is 7891200221.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1220021987 - 2⁶ = 1220021923 is a prime.

Together with 1220021989, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (1220021989) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610010993 + 610010994.

It is an arithmetic number, because the mean of its divisors is an integer number (610010994).

Almost surely, 2^1220021987 is an apocalyptic number.

1220021987 is a deficient number, since it is larger than the sum of its proper divisors (1).

1220021987 is an equidigital number, since it uses as much as digits as its factorization.

1220021987 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4032, while the sum is 32.

The square root of 1220021987 is about 34928.8131347173. The cubic root of 1220021987 is about 1068.5361491713.

The spelling of 1220021987 in words is "one billion, two hundred twenty million, twenty-one thousand, nine hundred eighty-seven".