1953998621 has 4 divisors (see below), whose sum is σ = 1973345244. Its totient is φ = 1934652000.

The previous prime is 1953998609. The next prime is 1953998659. The reversal of 1953998621 is 1268993591.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1318706596 + 635292025 = 36314^2 + 25205^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1953998621 is a prime.

It is a super-2 number, since 2×1953998621² = 7636221221739803282, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1953991621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9673160 + ... + 9673361.

It is an arithmetic number, because the mean of its divisors is an integer number (493336311).

Almost surely, 2^1953998621 is an apocalyptic number.

It is an amenable number.

1953998621 is a deficient number, since it is larger than the sum of its proper divisors (19346623).

1953998621 is a wasteful number, since it uses less digits than its factorization.

1953998621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19346622.

The product of its digits is 1049760, while the sum is 53.

The square root of 1953998621 is about 44204.0566124875. The cubic root of 1953998621 is about 1250.1863446991.

The spelling of 1953998621 in words is "one billion, nine hundred fifty-three million, nine hundred ninety-eight thousand, six hundred twenty-one".