18121649 has 32 divisors (see below), whose sum is σ = 24084480. Its totient is φ = 13234752.

The previous prime is 18121633. The next prime is 18121651. The reversal of 18121649 is 94612181.

It is a cyclic number.

It is not a de Polignac number, because 18121649 - 2⁴ = 18121633 is a prime.

It is not an unprimeable number, because it can be changed into a prime (18120649) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 81152 + ... + 81374.

It is an arithmetic number, because the mean of its divisors is an integer number (752640).

Almost surely, 2^18121649 is an apocalyptic number.

18121649 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

It is an amenable number.

18121649 is a deficient number, since it is larger than the sum of its proper divisors (5962831).

18121649 is a wasteful number, since it uses less digits than its factorization.

18121649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 309.

The product of its digits is 3456, while the sum is 32.

The square root of 18121649 is about 4256.9530182984. The cubic root of 18121649 is about 262.6632043299.

The spelling of 18121649 in words is "eighteen million, one hundred twenty-one thousand, six hundred forty-nine".