21190401 has 6 divisors (see below), whose sum is σ = 30608370. Its totient is φ = 14126928.

The previous prime is 21190349. The next prime is 21190409. The reversal of 21190401 is 10409112.

It can be written as a sum of positive squares in only one way, i.e., 15992001 + 5198400 = 3999^2 + 2280^2 .

It is not a de Polignac number, because 21190401 - 2²² = 16996097 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21190409) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1177236 + ... + 1177253.

It is an arithmetic number, because the mean of its divisors is an integer number (5101395).

Almost surely, 2^21190401 is an apocalyptic number.

It is an amenable number.

21190401 is a deficient number, since it is larger than the sum of its proper divisors (9417969).

21190401 is a wasteful number, since it uses less digits than its factorization.

21190401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2354495 (or 2354492 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 18.

The square root of 21190401 is about 4603.3032704787. The cubic root of 21190401 is about 276.7237228498.

Adding to 21190401 its reverse (10409112), we get a palindrome (31599513).

The spelling of 21190401 in words is "twenty-one million, one hundred ninety thousand, four hundred one".