21890061 has 16 divisors (see below), whose sum is σ = 33477120. Its totient is φ = 14122080.

The previous prime is 21890047. The next prime is 21890083. The reversal of 21890061 is 16009812.

It is not a de Polignac number, because 21890061 - 2¹⁵ = 21857293 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21890461) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12240 + ... + 13913.

It is an arithmetic number, because the mean of its divisors is an integer number (2092320).

Almost surely, 2^21890061 is an apocalyptic number.

It is an amenable number.

21890061 is a deficient number, since it is larger than the sum of its proper divisors (11587059).

21890061 is a wasteful number, since it uses less digits than its factorization.

21890061 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26193 (or 26187 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 27.

The square root of 21890061 is about 4678.6815450509. The cubic root of 21890061 is about 279.7364058399.

Adding to 21890061 its reverse (16009812), we get a palindrome (37899873).

The spelling of 21890061 in words is "twenty-one million, eight hundred ninety thousand, sixty-one".