1187721019 has 2 divisors, whose sum is σ = 1187721020. Its totient is φ = 1187721018.

The previous prime is 1187720981. The next prime is 1187721049. The reversal of 1187721019 is 9101277811.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1187721019 - 2¹⁷ = 1187589947 is a prime.

It is a super-2 number, since 2×1187721019² = 2821362437948796722, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1187721049) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 593860509 + 593860510.

It is an arithmetic number, because the mean of its divisors is an integer number (593860510).

Almost surely, 2^1187721019 is an apocalyptic number.

1187721019 is a deficient number, since it is larger than the sum of its proper divisors (1).

1187721019 is an equidigital number, since it uses as much as digits as its factorization.

1187721019 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7056, while the sum is 37.

The square root of 1187721019 is about 34463.3286117287. The cubic root of 1187721019 is about 1059.0215900579.

It can be divided in two parts, 11877 and 21019, that added together give a triangular number (32896 = T₂₅₆).

The spelling of 1187721019 in words is "one billion, one hundred eighty-seven million, seven hundred twenty-one thousand, nineteen".