1398865921 has 16 divisors (see below), whose sum is σ = 1448568576. Its totient is φ = 1350000000.

The previous prime is 1398865907. The next prime is 1398865939. The reversal of 1398865921 is 1295688931.

It is a 8-Lehmer number, since φ(1398865921) divides (1398865921-1)⁸.

It is a cyclic number.

It is not a de Polignac number, because 1398865921 - 2⁵ = 1398865889 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1398865991) 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, 1862296 + ... + 1863046.

It is an arithmetic number, because the mean of its divisors is an integer number (90535536).

It is a Proth number, since it is equal to 21345 ⋅ 2¹⁶ + 1 and 21345 < 2¹⁶.

Almost surely, 2^1398865921 is an apocalyptic number.

It is an amenable number.

1398865921 is a deficient number, since it is larger than the sum of its proper divisors (49702655).

1398865921 is a wasteful number, since it uses less digits than its factorization.

1398865921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1224.

The product of its digits is 933120, while the sum is 52.

The square root of 1398865921 is about 37401.4160293431. The cubic root of 1398865921 is about 1118.3867934245.

The spelling of 1398865921 in words is "one billion, three hundred ninety-eight million, eight hundred sixty-five thousand, nine hundred twenty-one".