15649421 has 2 divisors, whose sum is σ = 15649422. Its totient is φ = 15649420.

The previous prime is 15649399. The next prime is 15649429. The reversal of 15649421 is 12494651.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15642025 + 7396 = 3955^2 + 86^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-15649421 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (15649429) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7824710 + 7824711.

It is an arithmetic number, because the mean of its divisors is an integer number (7824711).

Almost surely, 2^15649421 is an apocalyptic number.

It is an amenable number.

15649421 is a deficient number, since it is larger than the sum of its proper divisors (1).

15649421 is an equidigital number, since it uses as much as digits as its factorization.

15649421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8640, while the sum is 32.

The square root of 15649421 is about 3955.9349084635. The cubic root of 15649421 is about 250.1301775368.

The spelling of 15649421 in words is "fifteen million, six hundred forty-nine thousand, four hundred twenty-one".