15138821 has 2 divisors, whose sum is σ = 15138822. Its totient is φ = 15138820.

The previous prime is 15138793. The next prime is 15138863. The reversal of 15138821 is 12883151.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 7924225 + 7214596 = 2815^2 + 2686^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-15138821 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (15135821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7569410 + 7569411.

It is an arithmetic number, because the mean of its divisors is an integer number (7569411).

Almost surely, 2^15138821 is an apocalyptic number.

It is an amenable number.

15138821 is a deficient number, since it is larger than the sum of its proper divisors (1).

15138821 is an equidigital number, since it uses as much as digits as its factorization.

15138821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1920, while the sum is 29.

The square root of 15138821 is about 3890.8637858450. The cubic root of 15138821 is about 247.3796769151.

The spelling of 15138821 in words is "fifteen million, one hundred thirty-eight thousand, eight hundred twenty-one".