20151949 has 2 divisors, whose sum is σ = 20151950. Its totient is φ = 20151948.

The previous prime is 20151947. The next prime is 20151959. The reversal of 20151949 is 94915102.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14478025 + 5673924 = 3805^2 + 2382^2 .

It is a cyclic number.

It is not a de Polignac number, because 20151949 - 2¹ = 20151947 is a prime.

It is a super-2 number, since 2×20151949² = 812202096997202, which contains 22 as substring.

Together with 20151947, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 20151949.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20151947) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10075974 + 10075975.

It is an arithmetic number, because the mean of its divisors is an integer number (10075975).

Almost surely, 2^20151949 is an apocalyptic number.

It is an amenable number.

20151949 is a deficient number, since it is larger than the sum of its proper divisors (1).

20151949 is an equidigital number, since it uses as much as digits as its factorization.

20151949 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3240, while the sum is 31.

The square root of 20151949 is about 4489.0922244926. The cubic root of 20151949 is about 272.1274498237.

The spelling of 20151949 in words is "twenty million, one hundred fifty-one thousand, nine hundred forty-nine".