20399961 has 8 divisors (see below), whose sum is σ = 27260064. Its totient is φ = 13569920.

The previous prime is 20399947. The next prime is 20399969. The reversal of 20399961 is 16999302.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20399961 - 2¹⁹ = 19875673 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20399969) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5880 + ... + 8681.

It is an arithmetic number, because the mean of its divisors is an integer number (3407508).

Almost surely, 2^20399961 is an apocalyptic number.

It is an amenable number.

20399961 is a deficient number, since it is larger than the sum of its proper divisors (6860103).

20399961 is a wasteful number, since it uses less digits than its factorization.

20399961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15031.

The product of its (nonzero) digits is 26244, while the sum is 39.

The square root of 20399961 is about 4516.6315988799. The cubic root of 20399961 is about 273.2392674862.

The spelling of 20399961 in words is "twenty million, three hundred ninety-nine thousand, nine hundred sixty-one".